indifferent adj.

word-forming element meaning "not, opposite of, without" (also im-, il-, ir- by assimilation of -n- with following consonant, a tendency which began in later Latin), from Latin in- "not," cognate with Greek an-, Old English un-, all from PIE root *ne- "not."

In Old French and Middle English often en-, but most of these forms have not survived in Modern English, and the few that do (enemy, for instance) no longer are felt as negative. The rule of thumb in English has been to use in- with obviously Latin elements, un- with native or nativized ones.

late 14c., "be unlike, dissimilar, distinct, or various," from Old French differer (14c.) and directly from Latin differre "to set apart, differ," from assimilated form of dis- "apart, away from" (see dis-) + ferre "to bear, carry," from PIE root *bher- (1) "to carry." Meaning "disagree, be of contrary opinion" is from 1560s.

Two senses that were present in Latin have gone separate ways in English in sense and spelling (probably based on different stress) since c. 1500, with defer (transitive) taking one set of meanings and differ (intransitive) the rest. Related: Differed; differing.