dis-prefix

In Latin, dis- was retained in full before c, p, q, s, t, sometimes before g, h, j, and usually before the vowels, where, however, it sometimes became dir- (as in diribēre = dis + habēre, dirimĕre = dis + emĕre); before f, it was assimilated, as dif- (as in dif-ferre, dif-fūsus); before the other consonants, it was reduced to dī- (di- prefix¹). In late Latin the full dis- was often restored instead of dī- (cf. English dismiss, disrupt); and the prefix itself became of more frequent use by being substituted in many words for Latin dē-: see de- prefix 1f. The regular Romanic form of dis- (dif-) was des- (def-) as in Old Italian, Spanish, Portuguese, Pr., Old French. In French s (f) before a consonant became mute, and was finally dropped in writing, giving modern French dé-. In Old French words of learned origin adopted from Latin, the Latin dis- was usually retained; and under the influence of these, dis- was often substituted for, or used alongside of, des- in the inherited words, e.g. descorder, discorder. The early Old French words in English exhibit the prefix in these forms; des- prevailing in the popular words, dis- (dys-) in those of learned origin. But before the close of the Middle English period, the latinized form dis- (dys-) was uniformly substituted, and des- became entirely obsolete, or was retained only in a few words in which its nature was not distinctly recognized, as descant n. All words taken from Latin in the modern period have dis-. Hence, in English, dis- appears (1) as the English and French representative of Latin dis- in words adopted from Latin; (2) as the English representative of Old French des- (modern French dé-, dés-), the inherited form of Latin dis-; (3) as the representative of late Latin dis-, Romanic des-, substituted for Latin dē-; (4) as a living prefix, arising from the analysis of these, and extended to other words without respect to their origin.In Latin, compounds in dis- were frequently the opposites of those in com-, con-; e.g. concolor of the same colour, discolor of different colours; concordia concord, discordia discord; conjunctio joining together, disjunctio separation; compendium profit, dispendium loss; consentīre to agree in feeling, dissentīre to disagree in opinion, etc. In classical Latin dis- was rarely prefixed to another prefix, though discondūcĕre to be unprofitable, is used by Plautus, and disconvenīre to disagree, by Horace; but in late Latin and Romanic, compounds in discon-, expressing the separation of elements of which com-, con- expressed the junction, became very numerous; many words of this type have come down through French into English, where others have been formed after them: cf. discoherent adj., discomfit v., discomfort n., discommend v., discompose v., discompound vb. at sense 2a, disconnect v., disconsolate adj., discontent adj., discontinue v.In some words beginning with dis-, the prefix is di-, the s being the initial of the radical (e.g. di-sperse, di-stinguish). But by identity of phonetic change, dis- here also became des- (sometimes reduced to de-) in Old French, whence also des- in Middle English as desperse, destincte; at the Renaissance these were rectified to dis-.