Origin and history of debase

late 14c., "low, of little height," from Old French bas "low, lowly, mean," from Late Latin bassus "thick, stumpy, low" (used only as a cognomen in classical Latin, humilis being there the usual word for "low in stature or position"), which is of uncertain origin, possibly from Oscan, or Celtic, or related to Greek basson, comparative of bathys "deep."

The meaning "low on the social scale" is from late 15c.; that of "low in the moral scale" is attested by 1530s in English. The meaning "befitting an inferior person or thing, unworthy" is from 1590s. Base metals (c. 1600) were worthless in contrast to noble or precious metals. Related: Basely.

"to lower in dignity, lower the standing of, debase," c. 1600, perhaps from de- "down" + mean (adj.) and modeled on debase. It is indistinguishable in some uses from obsolete demean (Middle English, from Old French demener; see demeanor) which likely influenced it and might be its ultimate source. It was much-criticized in late 19c. by purists (Fitzedward Hall, etc.), and Century Dictionary (1897) reports "the word is avoided by scrupulous writers." Related: Demeaned; demeaning.

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-.