forms adjectives: pertaining to, located in; As a prefix, a- is a privative (negating) morpheme meaning “without,” “not,” or “lacking” — indicating the absence of a structure, function, or condition. It attaches to Greek-derived roots. When the root begins with a vowel, it typically becomes an- to ease pronunciation. As a suffix, -a serves primarily as a grammatical/nominative ending in Latin and Greek nouns (especially neuter plural Latin forms and feminine singular forms), giving medical terms their standard noun form rather than carrying independent clinical meaning.
greek From Greek -akos — an adjectival suffix denoting “of,” “belonging to,” or “pertaining to.” Passed into Latin as -acus and into English via French -ac or directly from Latin/Greek. Closely related to the more common suffix -ic (also from Greek -ikos)