"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.
1958, proprietary name (Britain), from French vel(ours) cro(ché) "hooked velvet."
Here is a nonmetallic fastener with no mechanical parts. It is simply two strips of nylon, one woven with thousands of tiny protruding hooks, the other with loops. Pressed together, they catch like a burr to clothing, can't be parted except by peeling. American Velcro, Manchester, N.H., makes them to hold anything from pants to upholstery. [Popular Science, December 1958]
"collarbone," 1610s, from French clavicule "collarbone" (16c.), also "small key," from Medieval Latin clavicula "collarbone" (used c. 980 in a translation of Avicenna), special use of classical Latin clavicula, literally "small key, bolt," diminutive of clavis "key" (from PIE root *klau- "hook"); in the anatomical sense a loan-translation of Greek kleis "key, collarbone," which is from the same PIE source. So called supposedly from its function as the "fastener" of the shoulder. Related: Clavicular.
As an adjective from 1790. Commonly used to indicate instantaneous action, as in snap judgment (1841). Sense of "quick movement" is first recorded 1630s; that of "something easily done" is 1877. Meaning "brief or sudden spell" of weather (usually cold) is from 1740. Meaning "catch or fastener that closes with a snapping sound" is from 1815. The card game name is attested from 1881, from a call used in the game. Meaning "a snap-shot" is from 1894. U.S. football sense is from 1912, earlier snap-back (1880), which also was a name for the center position. Snap, Crackle and Pop, cartoon characters associated with Kellogg breakfast cereal Rice Krispies, are from 1940.