Origin and history of irrecognition

mid-15c., recognicion, "knowledge (of an event or incident); understanding," from Old French recognition (15c.) and directly from Latin recognitionem (nominative recognitio) "a reviewing, investigation, examination," noun of action from past-participle stem of recognoscere "to acknowledge, know again; examine" (see recognize).

Sense of "acknowledgment of a service or kindness done" is from 1560s. Sense of "formal avowal of knowledge and approval" (as between governments or sovereigns) is from 1590s; especially acknowledgement of the independence of a country by a state formerly exercising sovereignty (1824).

The meaning "a knowing again, consciousness that a given object is identical to an object previously recognized" is by 1798 (Wordsworth). The literary (especially stage) recognition scene "scene in which a principal character suddenly learns or realizes the true identity of another character" is by 1837 (in a translation from German).

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.