hot spot (n.)

Old English hat "hot, flaming, opposite of cold," used of the sun or air, of fire, of objects made hot; also "fervent, fierce, intense, excited," from Proto-Germanic *haita- (source also of Old Saxon and Old Frisian het, Old Norse heitr, Middle Dutch and Dutch heet, German heiß "hot," Gothic heito "heat of a fever"), of uncertain origin, perhaps related to Lithuanian kaisti "to grow hot;" both could be from a substratum word.

With a long vowel in Middle English (rhyming with boat, wrote) which shortened in modern English, perhaps from influence of comparative hotter. As an adverb, Old English hote.

Hot as "full of sexual desire, lustful" is from c. 1500; the sense of "inciting desire" is 18c. Taste sense of "pungent, acrid, biting" is from 1540s. Sense of "exciting, remarkable, very good" is 1895; that of "stolen" is first recorded 1925 (originally with overtones of "easily identified and difficult to dispose of"); that of "radioactive" is from 1942. Of jazz music or combos from 1924.

Hot flashes in the menopausal sense attested from 1887. Hot stuff for anything good or excellent is by 1889, American English. Hot seat is from 1933. Hot potato in figurative sense is from 1846 (from being baked in the fire coals and pulled out hot). Hot cake is from 1680s; to sell like hot cakes is from 1839.

The hot and cold in hide-and-seek or guessing games (19c.) are from hunting (1640s), with notion of tracking a scent. Hot and bothered is by 1921. Hot under the collar in the figurative sense is from 1895.

c. 1200, "moral stain;" by mid-14c. as "speck, stain left by something on a surface;" probably at least in part from a variant of Old English splott "a spot, blot, patch (of land)," and partly from or related to Middle Dutch spotte "spot, speck." Other cognates are East Frisian spot "speck," North Frisian spot "speck, piece of ground," Old Norse spotti "small piece," Norwegian spot "spot, small piece of land." Likely some of these Germanic words are borrowings of some of the others, but the exact evolution is unclear.

From c. 1300 as "patch or mark on the fur of an animal." The sense of "particular place, small extent of space" (on a body, etc.) is from late 14c. In general figurative use, "a blemish, defect, distinguishing mark," late 14c. Also from late 14c. as "an eruption on the skin."

The meaning "short interval in a broadcast for an advertisement or announcement" is by 1937, from earlier sense of "an act's position on a bill" 1923. Preceded by a number (as in five-spot) it originally was a term for "prison sentence" of so many years (1901, American English slang). The sense in night-spot is by 1954.

Colloquial phrase hit the spot "satisfy, be what is required" is by 1857. The adverbial phrase on the spot is attested by 1670s as "at once, without moving or delay;" 1680s as "in the precise place and time." Hence to be on the spot "doing just what is right and needed" (1884). To put (someone) on the spot "place in a difficult situation" is from 1928; to be in a spot "in difficulty" is by 1929. Spot check, made on a random sample, is attested by 1933; as a verb by 1944. Adverbial phrase spot on "completely right" attested from 1920.