Definition from Wiktionary, the free dictionary
dumbshit (plural dumbshits)
- (vulgar, pejorative, colloquial) A stupid person or someone who makes or has just made a significant mistake.
1968, Faith Sale, New writing: the Book-of-the-Month Club--College English Association award, volume 1-2, page 107:
- "You wanna be a dumbshit, I don't care."
dumbshit (not comparable)