chassis 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]

framed part of a window, into which the panes are fitted, 1680s, sashes, a mangled Englishing of French châssis "frame" of a window or door (see chassis).

The word was mistaken as a plural and further mangled by loss of the -s by 1704. Sash-door, one having panes of glass to admit light, is by 1726; sash-weight, attached by cords to either side of a sash to balance it and make it easier to raise and lower, is attested by 1737.

"art of engraving designs on metallic surfaces," from chase (v.) "to decorate metal work," mid-15c., short for enchase, from Old French enchassé "enclosed, framed," from en- "in" (see in- (2)) + chasse (see chassis).