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.
Smart Bomb Image Gallery. A dumb bomb is a bomb with only these elements, dropped from an airplane (such as the B-2 bomber). The bomb is considered dumb because it simply falls to the ground without actively steering itself. Needless to say, it's some feat hitting a target precisely with this type of weapon.