Body of water having same dimensions? (3)
I believe the answer is:
med
'body of water' is the definition.
(short for Mediterranean)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for med that I've seen before include "Sea (informal)" , "Mediterranean (colloq.)" , "Cote d'Azur sea" , "Sea (abbr)" .)