A-

A-: Prefix very much employed in medicine and all of the health sciences, indicating "not, without, -less" as, for example, in alexia (not read), aphagia (not eat), aphonia (not voice, voiceless).

The "a-" usually becomes "an-" before a vowel as, for example, in anemia (without blood), anophthalmia (no eye), anotia (no ear), anoxia (no oxygen).

The prefix "a-" comes from the Greek meaning "not."