An alpha privative or, rarely,[1] privative a (from Latin Latin: alpha prīvātīvum, from Ancient Greek Greek, Ancient (to 1453);: α στερητικόν) is the prefix a- or an- (before vowels) that is used in Indo-European languages such as Sanskrit and Greek and in words borrowed therefrom to express negation or absence, for example the English words of Greek origin atypical, anesthetic, and analgesic.
It is derived from a Proto-Indo-European syllabic nasal *, the zero ablaut grade of the negation *, i.e. /n/ used as a vowel. For this reason, it usually appears as Greek, Ancient (to 1453);: an- before vowels (e.g. an-alphabetism, an-esthesia, an-archy). It shares the same root with the Greek prefix Greek, Ancient (to 1453);: nē- or Greek, Ancient (to 1453);: ne-, in Greek Greek, Ancient (to 1453);: νη- or Greek, Ancient (to 1453);: νε-, that is also privative (e.g. Greek, Ancient (to 1453);: [[nepenthe|ne-penthe]]).
It is not to be confused with, among other things, an alpha copulative (e.g. a-delphós) or the prefix Greek, Ancient (to 1453);: an- (i.e. the preposition Greek, Ancient (to 1453);: aná with ecthlipsis or elision of its final vowel before a following vowel; e.g. Greek, Ancient (to 1453);: [[anode|an-ode]]).
The same prefix appears in Sanskrit, also as अ- Sanskrit: a- before consonants; and अन्- Sanskrit: an- before vowels.
In Latin, the cognate prefix is Latin: in-, which leaves its traces in English words like invisible and inaccessible. The prepositional prefix Latin: in- is unrelated.
In English and other West Germanic languages, the cognate is un- (or on-).
In North Germanic languages, the -n- has disappeared and Old Norse has Norse, Old: ú- (e.g. Norse, Old: [[Údáinsakr|ú-dáins-akr]]), Danish and Norwegian have Norwegian: u-, whereas Swedish uses Swedish: o- (pronounced [u]), and Icelandic and Faroese use the related Icelandic: [[wikt:en:ó-#Icelandic|ó-]].
The prefix Greek, Ancient (to 1453);: ἁ- Greek, Ancient (to 1453);: ha- (also Greek, Ancient (to 1453);: ἀ- Greek, Ancient (to 1453);: a- from psilosis), copulative a, is nearly homonymous with privative Greek, Ancient (to 1453);: a, but originates from Proto-Indo-European *.