mid-12c., forloren "disgraced, depraved," past participle of obsolete forlesan "be deprived of, lose, abandon," from Old English forleosan "to lose, abandon, let go; destroy, ruin," from for- "completely" + leosan "to lose" (from Proto-Germanic *lausa-, from PIE root *leu- "to loosen, divide, cut apart"). In the Mercian hymns, Latin perditionis is glossed by Old English forlorenisse. OED's examples of forlese end in 17c., but the past participle persisted. Sense of "forsaken, abandoned" is 1530s; that of "wretched, miserable" first recorded 1580s.
A common Germanic compound (cognates: Old Saxon farilosan, Old Frisian urliasa, Middle Dutch verliesen, Dutch verliezen, Old High German virliosan, German verlieren, Gothic fraliusan "to lose").
In English now often in forlorn hope (1570s), which is a partial translation of Dutch verloren hoop, in which hoop means "troop, band," literally "heap," and the sense of the whole phrase is of a suicide mission. The phrase more often than not is used in English as if it meant "a faint hope," and the misuse has colored the meaning of forlorn. Related: Forlornly; forlornness.
Old English colian, "to lose warmth," also figuratively, "to lose ardor;" cognate with Old Saxon kolon, Dutch koelen, Old High German chuolan, German kühlen, all from the root of cool (adj.). Transitive meaning "to cause to lose warmth, reduce the temperature of" is from late 14c. Related: Cooled; cooling.
Figurative meaning "abate the intensity of" is from c. 1300. To cool (one's) heels" wait in attendance, "generally applied to detention at a great man's door" [Century Dictionary] is attested from 1630s; probably the notion is "to rest one's feet after walking."
"act of treachery," 1834, from double (adj.) + cross (n.) in the sense of "pre-arranged swindle or fix." Originally to win a race after promising to lose it (to cheat in cheating, hence the double). As a verb from 1903, "to cheat," American English. Related: Double-crossed; double-crosser; double-crossing.
1827, "to afflict with panic," from panic (n.). Intransitive sense of "to lose one's head, get into a panic" is from 1902. Related: Panicked; panicking.
c. 1400, "moderate state of cold, coolness," from cool (adj.). Meaning "one's self-control, composure" (the thing you either keep or lose) is from 1966.
c. 1300, "grow weak, become enfeebled," also "lack courage or spirit, be faint-hearted," and "to pretend, feign;" from faint (adj.). Sense of "swoon, lose consciousness" is from c. 1400. Also used in Middle English of the fading of colors, flowers, etc. Related: Fainted; fainting. For Chaucer and Shakespeare, also a transitive verb ("It faints me").
"fall into disuse, grow obsolete," 1801, from Latin obsolescere "to grow old, wear out, lose value, become obsolete," inchoative of obsolere "fall into disuse" (see obsolete). Related: Obsolesced; obsolescing.
"to bring forth a calf or calves," Old English cealfian, from cealf "calf" (see calf (n.1)). Of glaciers, "to lose a portion by an iceberg breaking off," 1837. Related: Calved; calving.