In
Ancient Greek grammar,
privative a (also known as
privative alpha; in
Latin, α
prīvātīvum, in
Greek, α στερητικόν) is the
prefix a- that expresses negation or absence (e.g.
a-theos, ). It is derived from a
Proto-Indo-European syllabic nasal *, the zero
ablaut grade of the negation *
ne, i.e. /n/ used as a vowel. For this reason, it usually appears as
an- before vowels (e.g.
an-alphabetism,
an-esthesia,
an-archy). It shares the same root with the Greek prefix
nē or
ne, in Greek νη or νε, that is also privative (e.g.
ne-penthe).