(dumber, dumbest, dumbs dumbing dumbed)
1.
Someone who is dumb is completely unable to speak.
...a young deaf and dumb man.
= mute
ADJ
2.
If someone is dumb on a particular occasion, they cannot speak because they are angry, shocked, or surprised. (LITERARY)
We were all struck dumb for a minute.
= speechless
ADJ: v-link ADJ
• dumbly
I shook my head dumbly, not believing him.
ADV: ADV with v
3.
If you call a person dumb, you mean that they are stupid or foolish. (INFORMAL)
The questions were set up to make her look dumb.
ADJ [disapproval]
4.
If you say that something is dumb, you think that it is silly and annoying. (AM INFORMAL)
I came up with this dumb idea...
= stupid
ADJ [disapproval]