mid-14c., from un- (1) "not" + past participle of perceive (v.).
Entries linking to unperceived
un- 1
prefix of negation, Old English un-, from Proto-Germanic *un- (source also of Old Saxon, Old Frisian, Old High German, German un-, Gothic un-, Dutch on-), from PIE *n- (source of Sanskrit a-, an- "not," Greek a-, an-, Old Irish an-, Latin in-), combining form of PIE root *ne- "not." Often euphemistic (such as untruth for "lie").
The most prolific of English prefixes, freely and widely used in Old English, where it forms more than 1,000 compounds. It underwent a mass extinction in early Middle English, but emerged with renewed vigor 16c. to form compounds with native and imported words. It disputes with Latin-derived cognate in- (1) the right to form the negation of certain words (indigestable/undigestable, etc.), and though both might be deployed in cooperation to indicate shades of meaning (unfamous/infamous), typically they are not.
It also makes words from phrases (such as uncalled-for, c. 1600; undreamed-of, 1630s; uncome-at-able, 1690s; unputdownable, 1947, of a book; un-in-one-breath-utterable, Ben Jonson; etc., but the habit is not restricted to un-; such as put-up-able-with, 1812). As a prefix in telegramese to replace not and save the cost of a word, it is attested by 1936.
perceive v.
c. 1300, perceiven, "become aware of, gain knowledge of," especially "to come to know by direct experience," via Anglo-French parceif, Old North French *perceivre (Old French perçoivre) "perceive, notice, see; recognize, understand," from Latin percipere "obtain, gather, seize entirely, take possession of," also, figuratively, "to grasp with the mind, learn, comprehend," literally "to take entirely," from per "thoroughly" (see per) + capere "to grasp, take," from PIE root *kap- "to grasp."
Replaced Old English ongietan. Both the Latin senses were in Old French, though English uses the word almost always in the metaphorical sense. Related: Perceived; perceiving.