Which prefix indicates moving backward or behind?

• A. Con-
• B. Intra-
• C. Extra-
• D. Retro-

Answer: (D)

Retro- is the prefix that indicates moving backward or behind. It comes from Latin retro meaning "back" or "backward." In medical terms you’ll see it in retroperitoneal (behind the peritoneum), retrograde (moving backward along a path), and retrospective (looking back in time). This makes retro- the best fit for the idea of moving backward or behind. The other prefixes don’t convey backward direction: con- means with or together, intra- means within, and extra- means outside or beyond.