Meaning "to close by folding or bringing together" is from mid-14c. Meaning "prevent ingress and egress" is from mid-14c. Sense of "to set (someone) free (from)" (c. 1500) is obsolete except in dialectal phrases such as to get shut of. To shut (one's) mouth "desist from speaking" is recorded from mid-14c.
bolt-action breechloading rifle introduced into the French army 1866-68 and used by French forces in the Franco-Prussian War, 1870, named for French inventor Antonine-Alphonse Chassepot (1833-1905).
The modern use is mainly figurative and is perhaps from the word's use as synonym for king-bolt (itself from 1825), a large, thick, heavy bolt used in a machinery to couple large parts, but if this is the origin, the figurative use is attested earlier (1867) than the literal (1914).
"the human penis," Old English pintel, a word of uncertain origin; perhaps a diminutive (compare Old Frisian pint, Danish dialectal pint, German Pint). Extended use in reference to a pin or bolt upon which anything revolves is by late 15c.
also *kleu-, klēu-, Proto-Indo-European root meaning "hook, crook," also "crooked or forked branch" (used as a bar or bolt in primitive structures).
It forms all or part of: anschluss; autoclave; clause; claustrophobia; claves; clavichord; clavicle; clavier; claviger; clechy; clef; cloison; cloisonne; cloister; close (v.); close (adj.); closet; closure; cloture; clove (n.1) "dried flowerbud of a certain tropical tree, used as a spice;" cloy; conclave; conclude; disclose; enclave; enclose; exclude; foreclose; include; occlude; preclude; recluse; seclude; slot (n.2) "bar or bolt used to fasten a door, window, etc."
It is the hypothetical source of/evidence for its existence is provided by: Greek kleis "bar, bolt, key; collarbone," klobos "cage;" Latin clavis "key," clavus "nail," claudere "to shut, close;" Lithuanian kliūti "to catch, be caught on," kliaudžiu, kliausti "to check, hinder," kliūvu, kliūti "to clasp, hang;" Old Church Slavonic ključi "hook, key," ključiti "shut;" Old Irish clo "nail," Middle Irish clithar "hedge, fence;" Old High German sliozan "shut," German schließen "to shut," Schlüssel "key."
"morbid fear of being shut up in a confined space," coined 1879 (in article by Italian-born, French-naturalized Swiss-English physician Dr. Benjamin Ball), with -phobia "fear" + Latin claustrum "a bolt, a means of closing; a place shut in, confined place, frontier fortress" (in Medieval Latin "cloister"), from past participle of claudere "to close" (see close (v.)).
Proto-Indo-European root meaning "tooth, nail."
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit jambha-s "tooth;" Greek gomphos "peg, bolt, nail; a molar tooth;" Albanian dhemb "tooth;" Old English camb "comb."
king (n.) applied, at first in natural history, to species deemed remarkably big or dominant, such as king crab (1690s); the U.S. king snake (1737), which attacks other snakes and is regarded especially as the enemy of the rattlesnake; king cobra (1888). In marketing, king-size is from 1939, originally of cigarettes. A king-bolt (1825) was the large bolt connecting the fore part of a carriage with the fore-axle.
The King-snake is the longest of all other Snakes in these parts, but are not common; the Indians make Girdles and Sashes of their Skins, and it is reported by them, that they are not very venemous, and that no other Snake will meddle with them, which I suppose is the Reason that they are so fond of wearing their Skins about their Bodies as they do. [John Brickell, "The Natural History of North-Carolina," Dublin, 1737]
"U-shaped iron bar with holes at the ends for a bolt or pin, used as a fastener," 1590s, of unknown origin; perhaps from a Scandinavian source akin to Old Norse klofi "a cleft," from Proto-Germanic *klub‑ "a splitting," from PIE root *gleubh- "to tear apart, cleave." Also uncertain is whether it is originally a plural or a singular.