Which prefix means 'Against'?

• A. Contra-
• B. Retro-
• C. Intra-
• D. Mal-

Answer: (A)

Understanding prefixes that express opposition helps you decode terms quickly. The prefix that means “against” is contra-. It signals opposition or being on the opposite side or against a condition, as in contraindication (a treatment is not advised because it could be harmful) and contralateral (on the opposite side of the body). The other prefixes don’t convey opposition: retro- means backward or behind (retroflex, retrograde); intra- means within (intramuscular, intracardiac); mal- means bad or poorly (malpractice, malfunction). Therefore, contra- is the prefix that means “against.”