The privative a (also known as alpha privative or a privativum) is the prefix a- expressing negation (e.g. a-theism, atypical). Originally described for the grammar of Ancient Greek, it goes back to a PIE syllabic nasal *n̥-, the zero ablaut grade of the negation *ne. For this reason, it appears as an- before vowel (e.g. an-alphabetism, an-esthesia, an-archy). The same prefix appears in Sanskrit, also as a-, an-. In Latin, the cognate prefix is in-, and in West Germanic languages (including English) it is un-. In North Germanic languages, the -n- has disappeared and Old Norse, Danish and Norwegian have ú- (e.g. ú-dáins-akr), whereas Swedish has o-.

See also: copulative a

Indo-European linguistics | Hellenic languages and dialects