Definition of A- A-: Prefix indicating the absence or depletion of something: for example, aphagia (not eating) or aphonia (voiceless). The related prefix an- is usually used before a vowel, as in anemia (without blood) and anoxia (without oxygen).
A-: Prefix indicating the absence or depletion of something: for example, aphagia (not eating) or aphonia (voiceless). The related prefix an- is usually used before a vowel, as in anemia (without blood) and anoxia (without oxygen).