definition of
dumb

[1] #1 dumb s. [dense, dim, dull, obtuse, slow] slow to learn or understand; lacking intellectual acuity; "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 mak. wn

[2] #2 dumb s. [speechless] temporarily incapable of speaking; "struck dumb"; "speechless with shock". wn

[3] #3 dumb s. lacking the power of human speech; "dumb animals". wn

[4] #4 dumb s. [mute, silent] unable to speak because of hereditary deafness. wn