cassette (n.)

"receptacle, box, that which encloses or contains," early 14c., from Anglo-French and Old North French casse (Old French chasse "case, reliquary;" Modern French châsse), from Latin capsa "box, repository" (especially for books), from capere "to take, hold" (from PIE root *kap- "to grasp").

The meaning "outer protective covering" is from late 14c. Also used from 1660s with a sense of "frame" (as in staircase, casement). Artillery sense is from 1660s, from case-shot "small projectiles put in cases" (1620s). Its application in the printing trade (first recorded 1580s) to the two shallow wooden trays where compositors keep their types in compartments for easy access led to upper-case for capital letters (1862), so called from its higher position on the compositor's sloped work-table, and lower-case for small letters.

The cases, or receptacles, for the type, which are always in pairs, and termed the 'upper' and the 'lower,' are formed of two oblong wooden frames, divided into compartments or boxes of different dimensions, the upper case containing ninety-eight and the lower fifty-four. In the upper case are placed the capital, small capital, and accented letters, also figures, signs for reference to notes &c.; in the lower case the ordinary running letter, points for punctuation, spaces for separating the words, and quadrats for filling up the short lines. [The Literary Gazette, Jan. 29, 1859]

mid-15c., "small box for jewels, etc.," possibly a diminutive of English cask with -et, or from a corruption of French casset "a casket, a chest" (see cassette). Also a publisher's name for a collection of selected literary or musical pieces (1828). Meaning "coffin" (especially an expensive one) is American English, probably euphemistic, attested by 1832.

Thank Heaven, the old man did not call them "CASKETS!"—a vile modern phrase, which compels a person of sense and good taste to shrink more disgustfully than ever before from the idea of being buried at all. [Hawthorne, "Our Old Home," 1862]

1970, from video + cassette. Videocassette recorder is from 1971, usually VCR (also 1971), now a period piece.