Why was "tantrum" trending last week?
"defeated," c.1300; "wasted, spent in vain," c.1500; also "no longer to be found" (1520s), from past participle of lose. Lost Cause in reference to the Southern U.S. bid for independence is from the title of E.A. Pollard's history of the CSA and the rebellion (1866). Lost Generation in reference to the period 1914-18 first attested 1926 in Hemingway's "The Sun Also Rises," where he credits it to Gertrude Stein.
Old English losian "be lost, perish," from los "destruction, loss," from Proto-Germanic *lausa- (cf. Old Norse los "the breaking up of an army;" Old English forleosan "to lose, destroy," Old Frisian forliasa, Old Saxon farliosan, Middle Dutch verliesen, Old High German firliosan, German verlieren), from PIE root *leu- "to loosen, divide, cut apart, untie, separate" (cf. Sanskrit lunati "cuts, cuts off," lavitram "sickle;" Greek lyein "to loosen, untie, slacken," lysus "a loosening;" Latin luere "to loose, release, atone for, expiate").
Replaced related leosan (a class II strong verb whose past participle loren survives in forlorn and lovelorn), from Proto-Germanic *leusanan (cf. Old High German virliosan, German verlieren, Old Frisian urliasa, Gothic fraliusan "to lose").
Transitive sense of "to part with accidentally" is from c.1200. Meaning "fail to maintain" is from mid-15c. Meaning "to be defeated" (in a game, etc.) is from 1530s. Meaning "to cause (someone) to lose his way" is from 1640s. To lose (one's) mind "become insane" is attested from c.1500. To lose out "fail" is 1858, American English. Related: Lost; losing.