(Adj.) Used to describe a dubious or made up word, term, or phrase that is entirely plausible because it makes logical sense within existing language conventions.
Ironically, the word comulent itself is not cromulent. (See incromulent)
Origin: Television writer David X. Cohen for The Simpsons episode 3F13, "Lisa the Iconoclast".
My friend didn't believe me when I told her that meese was the plural of moose, but she admitted that it was entirely cromulent.