Extended sense of "nonhistorical or mythical story," with or without saints, wonders, and miracles is first recorded late 14c. Meaning "writing or inscription" (especially on a coin or medal) is from 1610s; on a map, illustration, etc., from 1903. To be a legend in (one's) own time is from 1958.
early 15c., "exposition of myths, the investigation and interpretation of myths," from Late Latin mythologia, from Greek mythologia "legendary lore, a telling of mythic legends; a legend, story, tale," from mythos "myth" (a word of unknown origin; see myth) + -logia (see -logy "study"). Meaning "a body or system of myths" is recorded by 1781.
"parti-colored, variegated with spots of different colors," late 14c. (early 14c. in surnames), as if it were the past participle of a verb form of the Middle English noun pie "magpie" (see pie (n.2)), in reference to the bird's black and white plumage. Earliest use is in reference to the pyed freres, an order of friars who wore black and white. Also in pied piper (1845, in Browning's poem based on the German legend; used allusively by 1939).
1709, "ancient Scandinavian legend of considerable length," an antiquarians' revival to describe the medieval prose narratives of Iceland and Norway, from Old Norse saga "saga, story," cognate with Old English sagu "a saying" (see saw (n.2)).
Properly a long narrative composition of Iceland or Norway in the Middle Ages featuring heroic adventure and fantastic journeys, or one that has their characteristics. The extended meaning "long, convoluted story" is by 1857.
coined 1958 by San Francisco newspaper columnist Herb Caen during the heyday of -nik suffixes in the wake of Sputnik. From Beat generation (1952), associated with beat (n.) in its meaning "rhythm (especially in jazz)" as well as beat (adj.) "worn out, exhausted," and Century Dictionary (1902) has slang beat (n.) "a worthless, dishonest, shiftless fellow." Originator Jack Kerouac in 1958 connected it with beatitude.
The origins of the word beat are obscure, but the meaning is only too clear to most Americans. More than the feeling of weariness, it implies the feeling of having been used, of being raw. It involves a sort of nakedness of the mind. [New York Times Magazine, Oct. 2, 1952]
"Beat" is old carny slang. According to Beat Movement legend (and it is a movement with a deep inventory of legend), Ginsberg and Kerouac picked it up from a character named Herbert Huncke, a gay street hustler and drug addict from Chicago who began hanging around Times Square in 1939 (and who introduced William Burroughs to heroin, an important cultural moment). The term has nothing to do with music; it names the condition of being beaten down, poor, exhausted, at the bottom of the world. [Louis Menand, New Yorker, Oct. 1, 2007]