Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
From natural infirmity (Ex. 4:11); not knowing what to say (Pr. 31:8); unwillingness to speak (Ps. 39:9; Lev. 10:3). Christ repeatedly restored the dumb (Mt. 9:32, 33; Lk. 11:14; Mt. 12:22) to the use of speech.