Etymology
Advertisement
hot water (n.)
c. 1400, literal; 1530s in figurative sense of "trouble." See hot (adj.) + water (n.1). Hot-water bottle is from 1895.
Related entries & more 
Advertisement
hot (adj.)

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.

Related entries & more 
water (n.2)

measure of quality of a diamond, c. 1600, from water (n.1), perhaps as a translation of Arabic ma' "water," which also is used in the sense "luster, splendor."

Related entries & more 
water (n.1)
Origin and meaning of water

Old English wæter, from Proto-Germanic *watr- (source also of Old Saxon watar, Old Frisian wetir, Dutch water, Old High German wazzar, German Wasser, Old Norse vatn, Gothic wato "water"), from PIE *wod-or, suffixed form of root *wed- (1) "water; wet."

To keep (one's) head above water in the figurative sense is recorded from 1742. Water cooler is recorded from 1846; water polo from 1884; water torture from 1928. Linguists believe PIE had two root words for water: *ap- and *wed-. The first (preserved in Sanskrit apah as well as Punjab and julep) was "animate," referring to water as a living force; the latter referred to it as an inanimate substance. The same probably was true of fire (n.).

Related entries & more 
water (v.)
Origin and meaning of water
Old English wæterian "moisten, irrigate, supply water to; lead (cattle) to water;" from water (n.1). Meaning "to dilute" is attested from late 14c.; now usually as water down (1850). To make water "urinate" is recorded from early 15c. Related: Watered; watering.
Related entries & more 
Advertisement
hot-wire (v.)
also hotwire, "bypass the ignition key to start a motor vehicle," 1966, from hot-wire (adj.), which is attested from 1889 in reference to electricity wires. Related: Hot-wired; hot-wiring.
Related entries & more 
water-moccasin (n.)
type of snake in the U.S. South, 1821, from water (n.1) + moccasin (q.v.).
Related entries & more 
hot-rod (n.)
also hot rod, 1945, American English, from hot (adj.) + rod (n.), here apparently in a sense of "hunk of metal" (the cars also were called hot iron).
Related entries & more 
hot-foot (adv.)
"hastily," c. 1300, from hot + foot (n.). As a verb in U.S. slang, from 1896. As the name of a prank played with matches, by 1934.
Related entries & more 
water-closet (n.)
"privy with a waste-pipe and means to carry off the discharge by a flush of water," 1755, from water (n.1) + closet (n.).
Related entries & more