Is Dumber grammatically correct?

Is Dumber grammatically correct? Here, the adjective form is dumb and the comparative form is dumber. By adding –er to the adjective, you show the difference between two things—that one action or person is dumber than another. This works for adjectives that have one or two syllables such as nice or pretty.

Here, the adjective form is dumb and the comparative form is dumber. By adding –er to the adjective, you show the difference between two things—that one action or person is dumber than another. This works for adjectives that have one or two syllables such as nice or pretty.