The addition of -ity to an adjective results in a shift of stress to the antepenultimate syllable; that is, words in -ity are stressed on the last syllable before the -ity, even in cases where this syllable is part of another suffix (as in words in -ability and -icity).
adjective, dumber, dumbest. 1. lacking intelligence or good judgment; stupid; dull-witted. 2. lacking the power of speech (offensive when applied to humans): a dumb animal.
Examples of dumb in a sentence. I'm not dumb enough to believe that. It was a dumb idea in the first place. He just stood there with a dumb grin on his face. This is one of the dumbest TV shows I've ever seen. It was dumb luck that we found this place at all. His success is just a matter of dumb luck.