1. [adj]  unable to speak because of hereditary deafness
2. [adj]  lacking the power of human speech; "dumb animals"
3. [adj]  unable to speak temporarily; "struck dumb"; "speechless with shock"
4. [adj]  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 make some really dumb decisions"; "he was either normally stupid or being deliberately obtuse"; "worked with the slow students"

1. \Dumb\, a. [AS. dumb; akin to D. dom stupid, dumb, Sw.
   dumb, Goth. dumbs; cf. Gr. ? blind. See {Deaf}, and cf.
   {Dummy}.]
   1. Destitute of the power of speech; unable; to utter
      articulate sounds; as, the dumb brutes.
            To unloose the very tongues even of dumb creatures.
                                                  --Hooker.
   2. Not willing to speak; mute; silent; not speaking; not
      accompanied by words; as, dumb show.
            This spirit, dumb to us, will speak to him. --Shak.
            To pierce into the dumb past.         -- J. C.
                                                  Shairp.
   3. Lacking brightness or clearness, as a color. [R.]
            Her stern was painted of a dumb white or dun color.
                                                  --De Foe.
   {Deaf and dumb}. See {Deaf-mute}.
   {Dumb ague}, or {Dumb chill}, a form of intermittent fever
      which has no well-defined ``chill.'' [U.S.]
   {Dumb animal}, any animal except man; -- usually restricted
      to a domestic quadruped; -- so called in contradistinction
      to man, who is a ``speaking animal.''
   {Dumb cake}, a cake made in silence by girls on St. Mark's
      eve, with certain mystic ceremonies, to discover their
      future husbands. --Halliwell.
   {Dumb cane} (Bot.), a west Indian plant of the Arum family
      ({Dieffenbachia seguina}), which, when chewed, causes the
      tongue to swell, and destroys temporarily the power of
      speech.
   {Dumb crambo}. See under {crambo}.
   {Dumb show}.
      (a) Formerly, a part of a dramatic representation, shown
          in pantomime. ``Inexplicable dumb shows and noise.''
          --Shak.
      (b) Signs and gestures without words; as, to tell a story
          in dumb show.
   {To strike dumb}, to confound; to astonish; to render silent
      by astonishment; or, it may be, to deprive of the power of
      speech.
   Syn: Silent; speechless; noiseless. See {Mute}.
   

2. \Dumb\, v. t.
   To put to silence. [Obs.] --Shak.
   

from natural infirmity (Ex. 4:11); not knowing what to say (Prov. 31:8); unwillingness to speak (Ps. 39:9; Lev. 10:3). Christ repeatedly restored the dumb (Matt. 9:32, 33; Luke 11:14; Matt. 12:22) to the use of speech.