Which prefix means outside?

Which prefix means outside?

• A. Endo-
• B. Retro-
• C. Epi-
• D. Exo-

Answer: (D)

Outside is conveyed by the prefix exo-. It signals that something lies on the outside, external, or away from the center. This shows up in terms like exocrine glands, which secrete outside the body into ducts, or exogenous factors, originating from outside the body. That clarity makes exo- the best match for the meaning "outside." By contrast, endo- means inside or within, epi- means upon or on top of, and retro- means behind or backward. So they describe other spatial or directional relationships, not outside.

Outside is conveyed by the prefix exo-. It signals that something lies on the outside, external, or away from the center. This shows up in terms like exocrine glands, which secrete outside the body into ducts, or exogenous factors, originating from outside the body. That clarity makes exo- the best match for the meaning "outside."

By contrast, endo- means inside or within, epi- means upon or on top of, and retro- means behind or backward. So they describe other spatial or directional relationships, not outside.