What does the prefix a- mean?

• A. Without, lack of
• B. Before
• C. Inner
• D. New

Answer: (A)

The prefix a- signals absence or negation, meaning without or lacking. In nutrition and health terms you’ll see it in words like anhydrous (without water) and anaerobic (without oxygen), and anemia (not enough red blood cells). This form comes from Greek, and sometimes appears as an- before certain sounds. The other options point to different prefixes—pre- means before, intra- or endo- means within, and neo- means new—so they don’t match the meaning of a- here.