"Ma'amin" - (m., pl. "ma'aminim"); one who believes; actually the "binyan," in this context meaning the grammatical form, is "hipheil," the "causative," rather than "pa'al," the "active," indicating a more pro-active verb. In other words, believing in something of a spiritual nature, requires an effort of the mind and the imagination of the individual, and is not merely a passive "act;" as in "Ani ma'amin be-Emunah Shelemah B'viat HaMashiach …" "I believe with perfect faith in the Coming of the 'Mashiach' (the Messianic Redeemer of Israel),…" the Twelfth Principle of the RAMBAM.

"Maasei Avot Siman L'Banim" - (m); the idea that the actions of the Forefathers are a model for the actions of the descendants; for example, Yaakov Avinu, Jacob our forefather, is described in the Bible, as elaborated in the Midrash, as having dealt with Esav, his twin brother but archenemy, in the following three ways: by "Tefila," Prayer, "Doron," the giving of gifts, as Yaakov sent a large gift to Esav, as they approached their fateful confrontation, and, if all else failed, "Milchamah," War; Yaakov was prepared to fight with his brother.

So should the Jewish People at all times of confrontation with their enemies, take that triple approach - first and foremost, Prayer to the Almighty, second, sending a gift to the enemy, indicating their desire to settle differences amicably, but always, as a last resort, to be ready to fight.

"Mabul" - (m., pl. "mabulim"); a flood, or the Great Flood, as in "Noach was rescued by G-d from the "Mabul."

"Machashavah" - (f., pl. "machashavot"); thought; sometimes used in the sense of Jewish Thought, in particular; as in "She was very happy in her new school because her teachers excelled in both "Halachah" and "Machashavah."

"Machzor" - Jewish Prayer Book, used on the Days of Awe, Rosh HaShanah and Yom HaKippurim, and on the three major holidays, Pesach, or Passover, Shavuot, and Sukkot. Prayers and Torah Readings are included which capture the spirit of these great holidays. A tiny sample: On Rosh HaShanah, "Malchiyot," Kingliness, "Zichronot," Remembrances, and "Shofarot," Sounds of the Shofar, which express the transcendent themes of Rosh HaShanah. First, the unique majesty of Hashem, the Holy King, His Knowledge of our innermost thoughts, and that He gave to Mankind the ultimate gift when He gave the Torah to the Jewish People amidst thunder and lightning and the rising call of the Shofar. The "Viduyim" (Confessions) which we recite on Yom Kippur until "Neilah," the "Closing of the Gates of Prayer," when our Judgments are sealed.

The Prayer "Tal" for Dew, symbolizing the renewal and liberation of Pesach, the chant of Akdamot, in which we attempt to express our gratitude for the Torah, on Shavuot, and the "Geshem" Prayer for Rain, in which we petition Hashem for that great life-sustaining gift (for which our appreciation is heightened from the perspective of the Northeast United States in the Summer of 5759 (1999), during which we are experiencing the worst drought of the century), and we recognize Hashem as our Redeemer from all manner of trouble throughout all of Jewish History, on the Holiday of Divine Protection, Sukkot.

"Maftir" - (m); the additional Torah reading added to the seven basic divisions of each Parshah, either a repetition of the last verses of the Parshah, or special holiday-related verses recited on the Chagim, or the person "called up" to recite the blessing on that portion of the Torah; related to the Hebrew root "PTR," meaning "to leave," since it is the last portion of each Parshah; as in (somewhat untranslatably) "BeShabbat 'Shuva' kor'im le-'Maftir' et haRav;" "On the (special Shabbat called) 'Shabbat Shuva,' the Shabbat of Repentance which falls between Rosh HaShanah and Yom Kippur, the honor of being 'called up' as 'Maftir' is given to the Rabbi."

"Magen Avraham" - Commentary of Rabbi Avraham "Abaleh" Gombiner (1637-1683) of Kalisz, Poland, on "Orach Chayim," the Section of the "Shulchan Aruch" that deals with the Laws of Daily Life and Holiday Behavior, such as the Laws concerning Rising in the Morning, the various Prayers, Special Prayers and Mitzvot of the Holidays.

"Magen Avraham" means "Shield of Avraham," a phrase taken from the "Shemoneh Esray" Prayer, obviously reflecting the author's name, and possibly using the name of the First of the "Avot" because the Laws dealt with in this section of the Shulchan Aruch are the most fundamental for the Jew to become familiar with and practice.

"Malach" - (m., pl. "Malachim"); a messenger; frequently used in the sense of a "messenger of G-d;" that is, an angel. An example is found in Yaakov's dream, in which he was shown a vision of a "Sulam mutzav Artzah, ve-hineh Malachei Elokim olim ve-yoredim bo," "a Ladder reaching to Heaven, with Angels of the L-rd ascending and descending upon it" (Bereshit 28:12). Another example, where both "messenger" in the human sense and "angel" in the heavenly sense are possible, is found in Bereshit (32:4) where the verse reads, "And Yaakov sent 'messengers' to Esav, his brother," where one Midrash says that, because of his close relationship with the Master of Heaven, he was actually permitted to dispatch angels on this mission.

"Malkah" - (f., pl. "Malkot"); queen; as in "Shabbat HaMalkah," "the Sabbath Queen;" or as in, "Malkot me-fursamot ve-tzidkaniyot behistoriah shel Am Yisrael hayu Esther HaMalkah u-Shlomtzion HaMalkah," "Famous and righteous queens in the History of the People of Israel were Queen Esther and Queen Shlom-Tziyon."

"Malkeinu" - (m.) our king; as in the Prayer "Avinu Malkeinu," "Our Father, Our King," authored by Rabbi Akiva and recited on Fast Days and the "Yamim Noraim," the High Holy Days, Rosh HaShanah and Yom Kippur

"Mapah" - Hebrew for "Table-Cover," the name of the great work of the RAMA, Rabbi Moshe Isserles, which represented the Halachic opinions of the Ashkenazic (Northern and Western Europe) Jewish World. This work was integrated with the "Shulchan Aruch," Hebrew for "Set Table," of Rabbi Yosef Karo, which represented the Halachic opinions of the Sephardic (Spain and North Africa, basically) Jewish World.

"Masechet" (alt. Masechta) (Aramaic; plural Masechtot); a "volume;" one of sixty three volumes of the Talmud

"Mashiach" - see here

Matrilineal Descent - determining descent by the mother; this is the method of determining religious identity; that is, from the point of view of biology, a child is Jewish if and only if its mother was Jewish; as opposed to patrilineal descent

"Mayim" - (m., pl. "maimot"); water; involved as a primary element on the Second and on the Third Days of Creation; when G-d separated the "upper" from the "lower" waters, and when G-d gathered them into one place, calling them "Yamim," Seas.

A human being is delivered at birth in a bag of waters; some say that one never forgets this experience; to drink water is one of the primary needs of life.

In Biblical and Temple times, the method of becoming spiritually "clean" after having become spiritually "unclean;" for example, by contact with a human corpse, involved being sprinkled with the ashes of a "Parah Adumah," a red heifer (cow) (regarded as a Divine decree, without need of explanation, though symbolic meanings have been attached), dissolved in water.

Another necessary ingredient in the process of regaining purity was and is immersion in a "Mikvah," a pool of "mayim chayim," "living (non-stagnant) waters." The word "Mikvah" is based on the root "hope." In the absence of a Mikvah, the ocean, or a river or a flowing lake will serve.

The Mikvah is used as an element of "Teshuvah," Repentance.

In marital law, the Mikvah is also a vital component. Those laws, regarding Sexual Discipline in Marriage, are generally referred to as "Taharat HaMishpacha," or family purity.

"Mechaber" - Hebrew for "The Compiler," Rabbi Yosef Karo, author of the Shulchan Aruch, described above under Mapah. The original "Shulchan Aruch," when covered with the "Mapah," allowed the creation of a "Super" (doesn't sound appropriate, somehow, but nevertheless it's true) Shulchan Aruch.

"Mechilah" - (f.; pl. "mechilot"); pardon; from G-d and from human beings whom we have harmed in some way. In case of sins against our fellow man, Hashem requires that we obtain the pardon of the injured party, before he will grant us forgiveness.

"Medaber" - (m.; pl. "Medaberim"); speaking, or the state-of-being capable of speech, a uniquely human feature; as in "Hu hayah Rosh HaMedaberim bechol makom," "He was the featured speaker everywhere;" or as in "Yesh arbaah matzavei metziut:: Domem, Nefesh, Chai, Medaber; dugmaot hem: sela, eitz, tzvi, ben-adam," "There are four states of being: Silent, Living, Animated, Speaking; examples are: a rock, a tree, a deer, a human being."

"Medinat Yisrael" - see here

"Megilat Esther" - the sacred document, telling the story of Purim, that was incorporated into the "TANACH," the acronym for the collection of works from the Torah, the "Five Books of Moses," the Neviim, the Prophets, and the K'tuvim, the Sacred Writings, that together make up the Hebrew Bible, at the request of Queen Esther and Mordechai.

"Melach" - (m.); Salt; Sodium Chloride (NaCl); a basic substance of Nature, but one which plays a crucial role in the spiritual life of the Jew. Because it was used until modern times as an effective preservative, it carries the connotation of "eternity;" as in Bamidbar 18:19 where the gifts of the sacrifices are described as "Brit Melach Olam Hi," "An Eternal Salt-Covenant." Its association with the idea of a "covenant," designed as a long-lasting agreement, makes it a perfect metaphor for the agreement between G-d and the Jewish People concerning their observance of the Torah, which is to last forever.

"Melech" - (m.; pl. "melachim"); King; as in "David, Melech Yisrael, Chai V'Kayam," "David, King of Israel, lives and exists."

Men of the Great Assembly - See "Anshei K'nesset HaGedolah"

Merit of the Forefathers - see "Zechut Avot"

"Mesorah" - (f., pl. "mesorot"); tradition; specifically, Jewish Tradition; as in "Transmission of the 'Mesorah' is the purpose of Jewish Education."

"Mezuzah" - (f., pl. "Mezuzot"); literally, the door-post of a house. In the context of Torah commands, it has the related meaning of a scroll affixed to the door-posts of one's house and the rooms within one's house. The Command to do so is found in Devarim 6:9, "And these words that I command you this day…you shall write them on the door-posts of your house and on your gates."

This Command commemorates the time in ancient Egypt that HaShem commanded the Jewish People to mark their door-posts with the blood of a lamb, the animal that was worshipped by the Egyptians, and that was used as a sacrifice by the Jewish People. So that when He brought the Tenth Plague, the Plague of the Killing of the First-Born upon the Egyptians, He would "Pass Over" (hence the name "Passover," or Pesach, for the Holiday that celebrates the Exodus) the houses whose door-posts were marked.

The "Mezuzah" is a small scroll of parchment on which are written two Biblical passages: they are, "Hear O Israel, the L-rd our G-d, the L-rd is One…" (Devarim 6:4-9) and "And it shall be that if you carefully observe My Commandments …" (Devarim 11:13-21)

Before the Mezuzah is affixed to one's door-post, one recites the following Berachah: "Blessed are You, L-rd our G-d, King of the universe, Who has sanctified us with His Commandments and has commanded us to Affix the Mezuzah."

The Mezuzah, in its case, is then nailed or screwed or glued to the right side of the door, in the upper third part of the door-post, leaning inward towards the interior of the house or the room. 

"Midah" - (f.; pl. "Midot); characteristic or attribute; Divine or human, a measure; as in "Shlosh Esray Midot," the Thirteen Attributes of Hashem;
or as in the principle that Hashem rewards and punishes "Midah K'neged Midah," "Measure for Measure;" or as in "Al pi din Torah, Sochayr Yehudi Tzarich le-hishtamesh bemishkalim u-midot yesharim," "According to the Law of the Torah, a Jewish merchant must use honest weights and measures."

"Midat HaDin" - (f.); the Divine Attribute of Strict Justice. Generally speaking, it is Hashem's "Midat HaDin" His Attribute of Strict Justice," which is most in evidence on "Rosh HaShanah," the "Day of Judgment."

"Midat HaRachamim" - (f.); the Divine Attribute, or Quality, of Mercy. Generally speaking, it is Hashem's "Midat HaRachamim," His Attribute of Mercy," which is most in evidence on "Yom Kippur," the "Day of Atonement." Shakespeare writes of this Attribute, or Quality, when practiced by human beings, in "The Merchant of Venice," as follows:

"Milchamah" - (f.; pl. "Milchamot"); war, conflict: as in "Ki Tetze LaMilchamah al Oyevecha," " When you go out to war against your enemies." (Devarim 21:10)

"Minhag"- (m., pl. “Minhagim”);a custom; in Jewish Law, the term is used in contradistinction to “Din” or “Halachah,” both of which mean the “Law,” or the “way to go.”  “Minhag” is more optional; for example, according to the “minhag” of the Ashkenazic Jewish community, a certain selection from the Prophets is read for the Haftarah on a given Shabbat, while according to the Sephardic Jewish community, a different selection from the Prophets is used.

"Minyan" - (pl. "minyanim"); quorum (generally ten men) required for praying as a "community," or for the public reading of the Torah, or for reciting the "Kaddish," or other ritual matters of special holiness.

"Miriam" - sister of Moshe and Aharon; prophetess and great leader of Israel; credited with being the source of miraculous well which traveled with the Jewish People in the desert

"Mishkan" - (pl. "Mishkanim") - Sanctuary, or Portable Temple. This was the first institutionalized mechanism for the presence of G-d on earth. It was moved from place to place with the Jewish People during the period of their forty year sojourn in the wilderness. Later, in the Land of Israel, before the Temple was built in Yerushalayim, the Mishkan was still present, and existed in a number of places, such as Shiloh, Nov and Givon.

"Mishlei" - See here

"Mitzvah" - (pl. "Mitzvot"); a Command of G-d. There are several types, including the following:

• Seven Commands of the "Sons of "Noach"/Noah (refers to all of humanity because the entire human race descended, according to the Torah, from the survivors of the Great Flood, the "Mabul.") These commands are presumably "built into" the soul or conscience of the human being. The seven commands are:
  
  a. Not to engage in the practice of idol-worship
  b. Not to "Bless (euphemism for "curse") the Divine Name
  c. Not to Murder
  d. Not to engage in Sexual Transgressions
  e. Not to engage in Theft
  f. To Establish a System of Courts for the Administration of Justice
  g. Not to eat a limb torn from a live animal (against cruelty to animals)

• Six hundred thirteen Commands of the Torah, binding upon the Jewish People, including:
  
  a. Two hundred forty eight Positive Commands (for example: "You shall eat Matzot for seven days" - ("Shemot"/Exodus 12:15) and "Honor your father and your mother" (Ibid. 20:12)) and
  b. Three hundred sixty five Negative Commands (for example: "You shall not murder" (Ibid. 20:13) and "You shall not curse a deaf person and You shall not put a stumbling block in the path of a blind person." ("Vayikra"/Leviticus 19:14))

"Moach" - (m., pl. "Mochot"); the brain; as in "Mah yoter chashuv, HaLev o HaMoach?" "What is more important, the heart or the brain?"

"Moed" - (pl. Moadim) - holiday; synonym of "chag;" either commanded by G-d in the Bible or instituted by the Rabbis or Prophets of the Anshei K'nesset HaGedolah, the Men of the Great Assembly.

"Mohn" - the miraculous food that was given to the Jewish People when they traveled through the desert for forty years. One of the miraculous characteristics of this food was that, according to the Bible, it did not fall on Shabbat, while a double portion fell on Friday. According to the Midrash, whatever a person liked in terms of food, he or she would taste in the "mohn."

Monday - "Yom Sheni" - the second day of the week; this has the same Hebrew equivalent as the Second Day of Creation because, according to Jewish Tradition, that "Day" was Monday

Monotheism - the belief in One G-d. This is considered one of the great contributions of "Avraham Avinu," Avraham our forefather. The Midrash teaches that "at age three, Avraham recognized his Creator!"

The child had looked at the complicated and beautiful world and determined that it was obvious that such a world, comparable to a palace, had to have a builder! He considered the sun as the builder but rejected that idea when the sun, with the arrival of night, set. Likewise were the moon and the stars considered and rejected. In desperation the child called out, "Who is the builder of the house?" Whereupon HaShem revealed Himself and said, "I am the Creator and Owner of the world."

There is another Monotheistic Religion in the world; namely Islam. The great advantage that makes Judaism incalculably superior to Islam is that the Oral Law is a part, if not the most important part, of the Jewish Religion, while Islam has no comparable Oral Law.

"Mordechai" - the hero of the Purim story, who risked his life by refusing to bow to the evil Haman, who would go on to formulate a genocidal plot against the Jewish People.

Moses - See "Moshe"

"Moshe" - the individual who became, by his own great effort, the greatest human being who ever lived; Chosen by G-d to lead the Jewish People out of Egypt, and to be main Teacher of Torah to the Jewish People. Called "Moshe Rabbeinu," Moshe our "Master," or "Teacher," because he was the teacher par excellence of all of Jewish History. Brother of Aharon and Miriam; son of Amram and Yocheved; raised in the palace of Pharaoh because rescued from the Nile by the daughter of Pharaoh. Called "Master of the Prophets," the "humblest of men," and, by G-d, "he is trustworthy in all of My Palace."

"Mussar" – (m., generally not used in pl.); morality, ethics; reproof or punishment; a moral movement, based on the study of traditional ethical literature. 

Probably the classic text in “Mussar” is “Pirkei Avot”, Ethics of the Fathers.

Some ideas of Mussar are the awesome potential of man to obtain the greatest spiritual heights, serene acceptance of whatever G-d causes to happen to one in life; not over-concern with matters of “Olam HaZeh,” “This World;” preferred is focus on “Olam HaBa,” the “World-to-Come”

Some luminaries of the Mussar school within Judaism were Rav Yisroel Salanter, Rav Eliezer Papo, Rav Yerucham Levovitz and Rav Yechiel Yaakov Weinberg.

In the sense of reproof, the word is used in the context of “mussar ha-neviim,” the warning or reproof of the prophets.

In the sense of punishment, the word is used in the context of “mussar HaShem,” “the punishment of HaShem.”