Third-person singular simple present indicative form of dumb.(verb)
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Use "dumbs" in a sentence
"The same could probably be said for any attention-seeking female who "dumbs" themselves down in this way."
"To approach this as an all or nothing argument dumbs down the conversation."
"In what I think is a compliment, you'd never guess that these red are partly made from California grapes, as they don't have any one overpowering quality that dumbs them down to fruit bomb status."