delibrate 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-.

place for books, late 14c., from Anglo-French librarie, Old French librairie, librarie "collection of books; bookseller's shop" (14c.), from Latin librarium "book-case, chest for books," and libraria "a bookseller's shop," in Medieval Latin "a library," noun uses of the neuter and fem., respectively, of librarius "concerning books," from Latin librarium "chest for books," from liber (genitive libri) "book, paper, parchment."

Latin liber (from Proto-Italic *lufro-) was originally "the inner bark of trees," and perhaps is from PIE *lubh-ro- "leaf, rind," a derivative of the PIE root *leub(h)- "to strip, to peel" (see leaf (n.)). Comparing Albanian labë "rind, cork;" Lithuanian luobas "bast," Latvian luobas "peel," Russian lub "bast," de Vaan writes that, "for want of a better alternative, we may surmise that liber is cognate with *lubh- and goes back to a PIE word or a European word 'leaf, rind.'"

The equivalent word in most Romance languages survives only in the sense "bookseller's shop" (French libraire, Italian libraria). Old English had bochord, literally "book hoard." As an adjective, Blount (1656) has librarious.