Sukkah - (pl. "Sukkot"); the decorated hut which the Jewish People is commanded to construct for temporary use (for more on this "temporariness, see Southern Hospitality) during the Holiday of (you guessed it) "Sukkot", and to live in it, as much as possible as one would live in one's permanent house, during the Holiday. The purpose is, as stated in the Torah, "so that your generations will know that I housed the Children of Israel in 'Sukkot' when I took them out of the Land of Egypt; I am the L-rd your G-d." ("Vayikra"/Leviticus 23:43)
There is a disagreement in the Talmud as to whether "Sukkot" in the above verse refers to the temporary huts which we construct today or to the "Clouds of Glory" which led and shielded and cleared the terrain for the Jewish People, during their forty year period of travel in the Desert of Sinai, on their way to the Land of Israel. Although both sides of that debate agree that both of the instruments of protection, one constructed by humans, the other set into place by the Creator, were present.
Taking into account the minimum height of the "Sechach," the Covering of the "Sukkah," which is 10 "Tefachim" (approximately 10 times 8 centimeters, 80 centimeters, or about 32 inches), and the minimum area defined by the "Talmud" as 7 by 7 "Tefachim," we come out with a minimum overall size for the "Sukkah" as that of an adult seated at his table, to use the expression of the Talmud.
There is, however, no maximum overall size for a Sukkah. It can be as large as Jerusalem, or the whole world, for that matter, as "Sukkot," especially, is the Holiday through which the Jewish People "reaches out" to include the whole world in its celebration.
Another construction element of the "Sukkah" besides the "Sechach," are the "defanot," the walls. Interestingly, there is no requirement for four walls, and not even three! Strictly speaking, it is sufficient, for a valid minimum "Sukkah," to have just two recognizable walls, plus a third "halachically valid" (which means "OK" according to Jewish Law") wall. (That third wall, let's call it the "virtual wall," must consist of the beginning of a wall, just a bit more than one "tefach" (about 8 centimeters or 3.2 inches) plus a "Tzurat HaPesach," a device called a "form of a door" the definition and laws of which are, as they say, "way beyond" the scope of this Glossary.)
The existing walls of the "Sukkah," two, three or four in number, may be made of any material, but must be sufficiently strong to remain standing in an "average wind," not such as you would find at the top of Mt. Washington (where the highest wind velocity ever recorded, 231 M.P.H., was measured). Nor, for that matter, a wind such as blew in the late and unlamented Hurricane Floyd, which wreaked havoc on the Eastern United States.
For more about the walls, including a fairy tale, see About the Walls.