Etymology: Originally a variant of on- prefix (showing a reduced form in unstressed position). Compare a- prefix³.Attested occasionally in Old English and much more commonly in Middle English. The prefix an- represents a reduced form in unstressed position of on- prefix, frequently before a following vowel (compare a- prefix³ which occurs frequently before a following consonant), as e.g. in anele v., aninne prep., anoven adv., anunder prep., anuppe prep. (all now obsolete or archaic); also occasionally (in Middle English) before a following consonant, as e.g. anburst v., anhit v. (both now obsolete), although these may represent the reflex of an unattested Old English form. The prefix was probably identified with an- , a phonetic variant of on- prefix in Old English (frequently but not exclusively in stressed position) that survived into early Middle English. In the case of on high at high adj. and n.² Phrases 3 the full form on prep. was subsequently restored. In anon adv., anent prep. the relationship with on- prefix is now opaque; compare also anneal v. In anhungered adj., apparently expanded < ahungered adj. by confusion of a- prefix⁴ ( < of- prefix) with a- prefix³.

Etymology: < ancient Greek ἀν- (privative) not, without, wanting (only occurring before a vowel, including aspirated vowels; before a consonant as ἀ- : see a- prefix⁶) < the same Indo-European base as un- prefix¹.Earliest in words borrowed < Greek, either directly or via Latin or French, e.g. anarchy n. Formations within English are found sparingly from the 17th cent. onwards (e.g. anaetiological adj.) and frequently from the 19th cent. Usually combining with second elements ultimately of Greek origin (e.g. anallagmatic adj., anantherous adj.), but sometimes also with elements ultimately of Latin origin (e.g. anangular adj., anovulation n.). Compare French an- (formations in which are attested from at least the 19th cent.).