Definitions for "Megillah"
(Heb., "scroll." Plural: megillot.) Term for five shorter books of the Bible—Shir Hashirim or Song of Songs, Ruth, Ekha or Lamentations, Kohelet or Eccelesiastes, and Esther—each of which fits on a single scroll and is chanted on a different Jewish holiday.
A scroll. Typically used as an abbreviation for the Scroll of Esther, but also applicaple to Torahs. Or in my experience, slang for a story that goes on and on.
(lit., "scroll"): when used as a proper noun without a modifier, it is generally a reference to the Scroll of Esther which relates the narrative commemorated by the holiday of *Purim
Keywords:  tractate, moed
a tractate in Moed.
(Yiddish) a long boring tediously detailed account; "he insisted on giving us the whole megillah"