- dis- (assimilated as dif- before -f-, to di- before most voiced consonants), prefix meaning 1. "lack of, not" (e.g. DISHONEST (Cf. dishonest)); 2. "do the opposite of" (e.g. DISALLOW (Cf. disallow)); 3. "apart, away" (e.g. DISCARD (Cf. discard)), from O.Fr. des- or directly from L. dis- "apart, in a different direction, between," figuratively "not, un-," also "exceedingly, utterly," from PIE *dis- "apart, asunder" (Cf. O.E. te-, O.S. ti-, O.H.G. ze-, Ger. zer-). The PIE root is a secondary form of *dwis- and thus is related to L. bis "twice" (originally *dvis) and to duo, on notion of "two ways, in twain." In classical Latin, dis- paralelled DE- (Cf. de-) and had much the same meaning, but in L.L. dis- came to be the favored form and this passed into Old French as des-, the form used for new 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.
Etymology dictionary. 2014.