decompose v.

active word-forming element in English and in many verbs inherited from French and Latin, from Latin de "down, down from, from, off; concerning" (see de), also used as a prefix in Latin, usually meaning "down, off, away, from among, down from," but also "down to the bottom, totally" hence "completely" (intensive or completive), which is its sense in many English words.

As a Latin prefix it also had the function of undoing or reversing a verb's action, and hence it came to be used as a pure privative — "not, do the opposite of, undo" — which is its primary function as a living prefix in English, as in defrost (1895), defuse (1943), de-escalate (1964), etc. In some cases, a reduced form of dis-.

c. 1400, compousen, "to write" (a book), from Old French composer "put together, compound; adjust, arrange; write" a work (12c.), from com- "with, together" (see com-) + poser "to place," from Late Latin pausare "to cease, lay down" (see pause (n.)).

Meaning influenced in Old French by componere "to arrange, direct" (see composite; also see compound (v.), pose (v.)), which gradually was replaced in French by composer. Similar confusion is found in expose, oppose, repose (v.2), transpose, etc.

Meaning "to make or form by uniting two or more things" is from late 15c. Sense of "be the substance or elements of, make up" is from 1540s. Sense of "invent and put (music) into proper form" is from 1590s. From c. 1600 as "bring into a composed state, to cal, quiet;" from 1650s as "place (parts or elements) in proper form, arrange."

In painting, "combine into an arrangement with artistic effect" (1782). In printing, "put into type" (1630s), but the usual term among printers was set. Related: Composed; composing. The printers' composing room is from 1737.