Wiktionary
alpha privative
n. (context grammar English) The prefix a- (or an- when prefixing a root which begins with a vowel) found in some English words of Greek derivation. It expresses negation or absence. The prefix has cognates in other Indo-European languages, including in- in Latin and un- in English.
WordNet
alpha privative
n. the negative prefix a- or un-
Usage examples of "alpha privative".
Again, Quichua has an 'alpha privative'--thus 'A-stani' means 'I change a thing's place.