dumb is the dictionary form of Dumber Definition of dumb
1
[ adjective ] slow to learn or understand; lacking intellectual acuity

Synonyms

slow dull obtuse dim dense

Examples

"so dense he never understands anything I say to him" "never met anyone quite so dim" "although dull at classical learning, at mathematics he was uncommonly quick"- Thackeray "dumb officials"

2
[ adjective ] lacking the power of human speech

Examples

"dumb animals"

3
[ adjective ] unable to speak temporarily

Synonyms

speechless

Examples

"struck dumb" "speechless with shock"

4
[ adjective ] unable to speak because of hereditary deafness

Synonyms

silent mute

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