Jacob - See "Yaakov"

Jew - see here

Job - see "Iyov"

Jonathan - see "Yehonatan"

Joseph - see "Yosef"

Jubilee Year - see "Yovel"

Judaism - see here

"Kabbalah" - Jewish Mysticism; basic book is the "Zohar," written by Rabbi Shimon bar Yochai in the Second Century, CE, while in hiding from the Romans. He was recording an ancient tradition, much less known because of its esoteric nature. Despite this aspect, it is understandable, and meaningful, apparently, for average Jews who delve into it, as its popularity in Chassidut demonstrates. On the other hand, on its deepest levels, it is somewhat dangerous, as we see from the account of the four great scholars who "entered the PARDES," from which only one; namely, Rabbi Akiva, emerged whole in mind and soul. "PARDES" is an acronym, representing the four basic branches of Torah knowledge, the "S" corresponding to "Sod," Secret, as "Torat HaSod," the Secret Torah, is another name for Kabbalah.

"Kaddish" - the prayer recited by a mourner for eleven months, after the loss of a loved one. The purpose of reciting the Kaddish is to accrue merit for the Departed Soul. It is interesting to note that in the Kaddish, there is not a word about death; it is entirely a recital of the greatness and holiness of G-d.

"Kallah" - (f., pl. "Kallot"); a bride; who accepts an object of value, generally a ring, from a man, her "Chatan," who has said, "You are hereby dedicated to me, by acceptance of this ring, according to the Law of Moshe and Israel."

The "Kallah" accepts the ring, thereby accepting and agreeing to the designation of herself, to the "Chatan," as his wife.

Seven blessings are recited, each referring to a different aspect of marriage.

The "Chatan" and the "Kallah" spend a few moments of privacy together to symbolically seal their marriage.

It is a great Mitzvah to bring joy to the "Chatan" and the "Kallah," who are compared at this time and for the first week of their marriage to a king and a queen, by singing and dancing joyously in their honor.

In the Shabbat "Zemirot," Table Songs, the Shabbat is compared to a "Kallah in her beautiful clothes, among her companions," on one of the happiest days of her life.

"Kavanah" - (f., pl. "Kavanot"); conscious thought, intention, concentration. When one prays to HaShem, one should try to do so with utmost "kavanah."

"Kavod" - (m.); honor or glory; as in "According to Pirkei Avot, if one seeks his own 'kavod,' his 'kavod' runs away from him."

"Kedushah" - (pl. "Kedushot"); Two related meanings:

1) holiness; a fundamental concept of Judaism. The basic meaning is separation from the "general" and dedication to the "particular," as in the "Kiddushin," betrothal, of a "kallah," a bride, to her "chasan," or groom. In this context, she dedicates herself to him exclusively, out of the population of all the men in the world, as he in turn promises to her absolute loyalty and protective concern. Similarly, the concept applies to time, as in the Holy Day of Shabbat and the Chagim, as well as to place, as in the Holy Land. It also applies to language, as in the Holy Hebrew Language, called so because it is the language of the Torah, it has no profanity, and among many other reasons, it is more than a set of symbols, as for example, the word "light" in English is merely a symbol for the real phenomenon of light, whereas the Hebrew word for light, "ohr," partakes, somehow, of the very essence of light. It applies to nations, as the Jewish People is called "a kingdom of priests and a holy nation."

2) a section of the Jewish Prayers when in the midst of the repetition of the Central Prayer by the Leader of the Prayers, the Congregation assumes the role of the angels and praises G-d with the three-fold repetition, "Holy, Holy, Holy is the L-rd G-d of Hosts! The Whole World is Full of His Glory!"

"Kever" - (m., pl. "kevarim"); a grave; as in "Avraham purchased land in Chevron for the "kever" of Sarah."

"Kiddush" - Prayer recited at the beginning of a festive meal on the Shabbat or the Holidays. The prayer describes the specific symbolism of the holiday - e.g. Pesach is the "Time of our Freedom," Shavuot is the "Time of the Giving of the Torah," Shabbat is the "Day which was first to be called 'Holy,' commemorating both the Creation of the Universe and the Exodus from Egypt. The Kiddush contains, as well, information as to who is responsible for the conferring of the quality of "holiness" upon the day. In the case of Shabbat, on one hand, it was G-d Himself, Who made the Day holy, whereas it is the Jewish People that has been charged with the responsibility by the Torah and by its Author, to confer the holiness upon them, by means of establishing the calendar.

"Kiddush HaShem" - Sanctification of the name of HaShem. This great accomplishment is achieved generally in three ways:

By living a life of obeying HaShem's Commandments, as found in the Torah, rendering all aspects of life no longer "profane," but raising them to the level of the "holy", as he or she interacts with their spouse, children, family members, business associates, community members, friends, and with HaShem Himself in the manner and spirit built by the Divine Author into the Torah

When a Jew performs an act in public requiring unusual courage, risk, honesty or integrity, as for example, when Senator Joseph Lieberman, who had indeed been a friend of the President, rose to criticize the immorality displayed by the Chief Executive, by engaging in various acts that shed no glory on the Office of the Presidency of the United States.

By giving up one's life, if necessary, rather than submit to the betrayal of one's belief in G-d, and abandonment of Judaism for another religion, as many communities and countless individuals chose to do throughout Jewish History.

"Kiddushin" - betrothal, or formal engagement. This is the ceremony where the "chasan," the groom, places an object of some value, generally a plain ring, in the bride's hand, and declares the Hebrew equivalent of, "Behold, you are now betrothed unto me by this ring, according to the Law of Moses and Israel. " At this point, the "chasan" and "kallah" are considered to be married, in the sense that that she is forbidden to any other man. But bride and groom may not live intimately with each other until the ceremony of "yichud," "spending a short amount of time with each other in complete privacy." That process completes their wedding.

"Kitniot" - (from the OU "Glossary" of Common Passover Terms, except for the remarks in parentheses); Leguminous vegetables such as beans, peas, corn and rice. The consumption of these foods is restricted (on "Pesach"/Passover) by European Rabbinic Tradition, though these foods are not "Chametz." (The reason for this prohibition is probably based on the fact that these foods were frequently used in those locations to make what was called, and what looked like, "bread.") Unlike "Chametz," benefit from and possession of Kitniot during Passover are permitted.

Yeminite, Sefardic and Oriental Jews are not bound to this custom by their traditions. The tradition of the Kitniot restriction has been steadfastly maintained by all Jews of European origin for centuries. This includes the Jews of France, England, Germany, Russia, Poland, Hungary, Austria and the Low Countries.

"Klal Yisrael" – the Community of Israel; the Jewish People, as a whole.

"Kochav" - (m., pl. "Kochavim"); a star, one of the heavenly bodies created by HaShem on the fourth "Day of Creation" and placed at a great distance from the earth, to provide additional light at night, adding to that provided by the moon, the "Maor HaKatan," the "Small Light." Another purpose they serve is to display the infinite might of HaShem, Who Alone knows them all, as it says "The One Who counts them out by number; He knows the name of each." Whereas they are uncountable by a finite human being, as HaShem said to Avraham in Bereshit (15:5), "…look at the heavens, and count the stars, if you can count them…"

"Kohen" (alt. "Cohen") - (pl. "Kohanim" or "Cohanim") - Priest; Judaism is not a classless society; rather, there are three "classes" within the structure of Jewish society: Kohen, Levi and Yisrael. The Kohen is a descendant of Aharon, the High Priest, the brother of Moshe. His task is to work in the Temple, be involved with the offering of sacrifices, and with Blessing the Congregation of Israel. The Priest holds the highest status in the People of Israel, thus he is called up to the Torah first, and has first rights in leading the "Zimun" before the Birchat HaMazon. Since he did not participate in the "Goral," or Lottery, which divided the Land of Israel, he is the recipient of certain parts of some of the sacrifices, and of various "Matnot Kehunah," "Obligatory Presents to the Priests,' such as Terumah. The Kohanim are a subset of the Tribe of Levi. Thus, every Kohen is a Levi, but not every Levi is a Kohen.

"Lag BaOmer" - The thirty-third Day of Sefirat HaOmer ("Lag" is the pronunciation of the two Hebrew letters whose "gematria," the sum of the numerical equivalents (for example, num eq. of Aleph is 1, num. Eq. of Bet is 2, etc.) of each, similar to the game of Scrabble, equals "33"). On this Day, according to Tradition, the students of Rabbi Akiva, 24000 of whom had perished in a terrible plague, stopped dying. The Day is also the "yahrtzeit" (Yiddish for "death anniversary") of Rabbi Shimon bar Yochai. The day is a break in the partial mourning of the Sefira Period. Students go on outings with their teachers, families have picnics, and tens of thousands of Jews light bonfires, dance and sing at Meron, in the Galil in Israel, the burial place of Rabbi Shimon bar Yochai, who wrote the Zohar, and his son.

"Lashon Hara" – (f., not usually found in the plural); slander or malicious gossip, whether true or false.  “Lashon Hara,” and general inconsiderateness and hostility towards one’s fellow human beings, was one of the principal reasons for the destruction of the Second Temple.

Lazarus, Emma - see here

"Leah" - One of the "Founding Mothers" of the Jewish People; older sister of Rachel, daughter of Lavan, wife of Yaakov, described in Megillat Ruth as "…May Ruth be like Leah and Rachel, the two of whom together built the House of Israel…" (Ruth 4:11) Leah became the wife of Yaakov by a bit of a "trick," perpetrated by Lavan, based on the principle of "It's not done that way here, to have the younger one, namely Rachel, whom Yaakov had contracted to work for, for seven years, marry before the older one." (Bereshit 29:23) This was perhaps to keep Yaakov "in line," since he had on occasion been not entirely truthful, due to the difficult circumstances he faced, although it is he who is called in Jewish Tradition, the "Master of Truth." Some of the names that Leah gave her children reflect her unhappiness at being the less-loved wife, for example Shimon, because "Hashem has heard that I am the hated one" (Bereshit 29:33) and Levi, concerning whom she said "Maybe this time my husband will consent to be with me, for I have borne him now three sons." (Bereshit 29:34)

"Lev" - (m., pl. "Levavot"); the heart; as in "Lev tahor bera li Elokim," "Create for me a pure heart"

"Levi" - (pl. Leviim) - Levites; descendants of Levi, the son of Yaakov. Their task is to assist the Kohanim in matters relating to the Temple. Back in the desert, when the Jewish People carried the Mishkan from place to place, it was the task of the Leviim to carry the various components of the Mishkan, from the boards to the holy vessels from one destination to another. It is also the task of the Leviim to be the choir in the Temple; thus, for example, they would sing the "Psalm (Song of Praise) of the Day" and play the various instruments in the Temple. They were also the gatekeepers of the Temple. Since, like the Kohanim they are not given land in Israel, they are the recipients of "Maaser," one tenth the produce, or income, of each of the other tribes.

Leviticus - See "Vayikra"

"Luach" - (f., pl. "luchot"); tablet upon which information is inscribed; specifically, the Ten Commandments, as in "Moshe broke the first "luchot" because the Jewish People were worshipping the Golden Calf."

"Luchot" – (m., this is pl.; sing. “Luach”); tablets; specifically, the stone tablets upon which were inscribed the Ten Commandments; Moshe broke the first “luchot,” when he saw the Jewish People engaged in the Sin of the Golden Calf; he was allowed to re-inscribe them on a second set of “luchot” after HaShem forgave the People.  Both sets of “luchot” were kept in the Mishkan.