Prefix with Atlantic (3)

I believe the answer is:

mid

(Other definitions for mid that I've seen before include "Of the central part" , "Dim sort of prefix" , "Prefix meaning centre" , "Denote the centre point" .)

I've seen this clue in the New York Times and the LA Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.