tenterhooks (n.)

c. 1300, "wooden framework for stretching cloth," of uncertain origin, probably via Old French (but the evolution of the ending is obscure), and ultimately from Latin tentorium "tent made of stretched skins," from tentus "stretched," variant past participle of tendere "to stretch," from PIE root *ten- "to stretch."

"bent or angled piece of metal or other substance used to catch or hold something," Old English hoc "hook, angle," perhaps related to Old English haca "bolt," from Proto-Germanic *hokaz/*hakan (source also of Old Frisian hok, Middle Dutch hoek "a hook;" Dutch haak "a hook, angle, corner, cape," German Haken "hook"), from PIE root *keg- "hook, tooth." For spelling, see hood (n.1).

Also the name of a fireman's tool for tearing into buildings, hence hook-and-ladder (1821). Meaning "holder for a telephone receiver" is from 1885 and continued in use after the mechanism evolved. Boxing sense of "short, swinging blow with the elbow bent" is from 1898. Figurative sense "that which catches, a snare, trap" is from early 15c. Meaning "projecting point of land" is from 1670s; in U.S. use probably reinforced by the Dutch word.

This name is given in New York to several angular points in the North and East rivers; as Corlear's Hook, Sandy Hook, Powles's Hook. [Bartlett, "Dictionary of Americanisms," 1848]

Off the hooks meant "disordered" (16c.), "unhinged" (1610s) and "dead" (1840). By hook or by crook (late 14c.) probably alludes to tools of professional thieves. Hook, line, and sinker "completely" is 1838, a metaphor from angling. Hook-nose (n.) is from 1680s; hook-nosed (adj.) from 1510s. Hook-and-eye as a method of garment fastening is from 1620s.

Hook and eye, a metallic fastening for garments, consisting of a hook, commonly of flattened wire bent to the required shape, and an eye, usually of the same material, into which the hook fits. Under the name of crochet and loop, this form of fastening was in use as early as the fourteenth century. [Century Dictionary]

Proto-Indo-European root meaning "to stretch," with derivatives meaning "something stretched, a string; thin."

It forms all or part of: abstain; abstention; abstinence; abstinent; atelectasis; attend; attenuate; attenuation; baritone; catatonia; catatonic; contain; contend; continue; detain; detente; detention; diatonic; distend; entertain; extend; extenuate; hypotenuse; hypotonia; intend; intone (v.1) "to sing, chant;" isotonic; lieutenant; locum-tenens; maintain; monotony; neoteny; obtain; ostensible; peritoneum; pertain; pertinacious; portend; pretend; rein; retain; retinue; sitar; subtend; sustain; tantra; telangiectasia; temple (n.1) "building for worship;" temple (n.2) "flattened area on either side of the forehead;" temporal; tenable; tenacious; tenacity; tenant; tend (v.1) "to incline, to move in a certain direction;" tendency; tender (adj.) "soft, easily injured;" tender (v.) "to offer formally;" tendon; tendril; tenement; tenesmus; tenet; tennis; tenon; tenor; tense (adj.) "stretched tight;" tensile; tension; tensor; tent (n.) "portable shelter;" tenterhooks; tenuous; tenure; tetanus; thin; tone; tonic.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit tantram "loom," tanoti "stretches, lasts," tanuh "thin," literally "stretched out;" Persian tar "string;" Lithuanian tankus "compact," i.e. "tightened;" Greek teinein "to stretch," tasis "a stretching, tension," tenos "sinew," tetanos "stiff, rigid," tonos "string," hence "sound, pitch;" Latin tenere "to hold, grasp, keep, have possession, maintain," tendere "to stretch," tenuis "thin, rare, fine;" Old Church Slavonic tento "cord;" Old English þynne "thin."