dismantle v.

word-forming element of Latin origin meaning 1. "lack of, not" (as in dishonest); 2. "opposite of, do the opposite of" (as in disallow); 3. "apart, away" (as in discard), from Old French des- or directly from Latin dis- "apart, asunder, in a different direction, between," figuratively "not, un-," also "exceedingly, utterly." Assimilated as dif- before -f- and to di- before most voiced consonants.

The Latin prefix is from PIE *dis- "apart, asunder" (source also of Old English te-, Old Saxon ti-, Old High German ze-, German zer-). The PIE root is a secondary form of *dwis- and thus is related to Latin bis "twice" (originally *dvis) and to duo, on notion of "two ways, in twain" (hence "apart, asunder").

In classical Latin, dis- paralleled de- and had much the same meaning, but in Late Latin dis- came to be the favored form and this passed into Old French as des-, the form used for compound words formed in Old French, where it increasingly had a privative sense ("not"). In English, many of these words eventually were altered back to dis-, while in French many have been altered back to de-. The usual confusion prevails.

As a living prefix in English, it reverses or negatives what it is affixed to. Sometimes, as in Italian, it is reduced to s- (as in spend, splay, sport, sdain for disdain, and the surnames Spencer and Spence).

Old English mentel "a loose, sleeveless garment worn as an outer covering, falling in straight lines from the shoulders," from Latin mantellum "cloak" (source of Italian mantello, Old High German mantal, German Mantel, Old Norse mötull), perhaps from a Celtic source, or, if the Latin word is the same word as mantelum, mantelium "a cloth, hand-towel, napkin," perhaps it is from manus "hand."

Reinforced and altered 12c. by cognate Old French mantel "cloak, mantle; bedspread, cover" (Modern French manteau), also from the Latin source. Figurative sense "that which enshrouds, something that conceals, a covering" is from c. 1300. Allusive use for "symbol of literary authority or artistic pre-eminence" (by 1789) is from Elijah's mantle (II Kings ii.13). As a layer of the earth between the crust and core (though not originally distinguished from the core) it is attested from 1940. To take (originally have) the mantel (and the ring) was a symbolic act done before a bishop by a widow, indicating a vow of chastity (c. 1400).