late Old English plot "small piece of ground of defined shape," a word of unknown origin. The sense of "ground plan," and thus "map, chart, survey of a field, farm, etc." is from 1550s. Plat is a Middle English collateral form. The meaning "a secret, plan, fully formulated scheme" (usually to accomplish some evil purpose) is from 1580s, probably by accidental similarity to complot, from Old French complot "combined plan" (compare the sense evolution of plan), itself a word of unknown origin, perhaps a back-formation from compeloter "to roll into a ball," from pelote "ball." OED says "The usage probably became widely known in connexion with the 'Gunpowder Plot.' "
The meaning "set of events in a story, play, novel, etc." is from 1640s. Plot-line (n.) "main features of a story" is attested by 1940; earlier, in theater, "a sentence containing matter essential to the comprehension of the play's story" (1907).
c. 1300, "falsehood, fictitious narrative; a lie, pretense," from Old French fable "story, fable, tale; drama, play, fiction; lie, falsehood" (12c.), from Latin fabula "story, story with a lesson, tale, narrative, account; the common talk, news," literally "that which is told," from fari "speak, tell," from PIE root *bha- (2) "to speak, tell, say."
Restricted sense of "animal story" (early 14c.) comes from the popularity of Aesop's tales. In modern folklore terms, defined as "a short, comic tale making a moral point about human nature, usually through animal characters behaving in human ways" ["Oxford Dictionary of English Folklore"].
The fable which is naturally and truly composed, so as to satisfy the imagination, ere it addresses the understanding, beautiful though strange as a wild-flower, is to the wise man an apothegm, and admits of his most generous interpretation. When we read that Bacchus made the Tyrrhenian mariners mad, so that they leapt into the sea, mistaking it for a meadow full of flowers, and so became dolphins, we are not concerned about the historical truth of this, but rather a higher poetical truth. We seem to hear the music of a thought, and care not If the understanding be not gratified. [Thoreau, "A Week on the Concord and Merrimack Rivers"]
type of confection, 1895, American English, apparently a word first used among students at women's colleges; perhaps a special use from fudge (v.) or its noun derivative, via the notion of "insubstantial" or of something "faked-up" on the spot. The verb was used in school slang, and compare fudge (n.) "a made-up story" (1797).
'He lies,' answered Lord Etherington, 'so far as he pretends I know of such papers. I consider the whole story as froth — foam, fudge, or whatever is most unsubstantial. ...' [Scott, "St. Ronan's Well," 1823]
1711, "a low story between two higher ones in a building," from French mezzanine (17c.), from Italian mezzanino, from mezzano "middle," from Latin medianus "of the middle," from medius (from PIE root *medhyo- "middle"). Sense of "lowest balcony in a theater" recorded by 1913.