case (n.2)youdaoicibaDictYouDict[case 词源字典]
"receptacle," 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" (see capable).

Meaning "outer protective covering" is from late 14c. Also used from 1660s with a sense "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 trays where compositors keep their types in separate compartments for easy access led to upper-case letter for a capital (1862) 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]
[case etymology, case origin, 英语词源]