Which prefix means "without"?

The prefix that means "without" is the one commonly represented by "a-" or "an-." In medical terminology, "a-" is typically used before consonants, while "an-" is used before vowels. Both prefixes convey the absence of something or negate concepts associated with the root word.

For example, "aseptic" means without infection, and "anemia" refers to a condition without enough healthy red blood cells. These prefixes are essential in forming terms that describe conditions, processes, and medical concepts where the negation of a specific quality or element is crucial.

The other prefixes do not convey the meaning of "without"; for instance, "ab-" suggests a movement away from something, while "ad-" implies movement towards something. Their meanings are contextually different from the notion of absence that "a-" or "an-" communicates.