1. (Science: prefix) a prefix from the latin, whence f. Des, or sometimes de-, dis-. The latin dis- appears as di- before b, d, g, l, m, n, r, v, becomes dif- before f, and either dis- or di- before j. It is from the same root as bis twice, and duo, E. Two. See two, and cf. Bi-, di-, dia-. Dis- denotes separation, a parting from, as in distribute, disconnect; hence it often has the force of a privative and negative, as in disarm, disoblige, disagree. Also intensive, as in dissever.
walkers rule of pronouncing this prefix is, that the s ought always to be pronounced like z, when the next syllable is accented and begins with a flat mute [b, d, v, g, z], a liquid [l, m, n, r], or a vowel; as, disable, disease, disorder, disuse, disband, disdain, disgrace, disvalue, disjoin, dislike, dislodge, dismay, dismember, dismiss, dismount, disnatured, disrank, disrelish, disrobe. dr. Webster's example in disapproving of walkers rule and pronouncing dis- as diz in only one (disease) of the above words, is followed by recent orthoepists. See disable, Disgrace, and the other words, beginning with dis-, in this dictionary.