dumb

UK: /ˈdʌm/ US: /dʌm/ ,(dum)

Inflections of 'dumb' (adj):

dumber

adj comparative

dumbest

adj superlative

WordReference Random House Learner's Dictionary of American English © 2025

dumb /dʌm/   adj., -er, -est. 

1. lacking intelligence or good judgment;
   stupid;
   dull-witted:
   He was dumb to try a stunt like that.
2. stupid;
   silly;
   useless:
   What a dumb idea!
3. lacking the power of speech (often considered offensive when applied to humans):
   a dumb animal.
4. temporarily unable to speak:
   We were all dumb with astonishment at his outrageous comments.
5. refraining from any or much speech;
   silent:
   I kept dumb.
6. made, experienced, etc., without speech:
   in a dumb, furious rage.
7. Computing lacking electronic processing power of its own:
   a dumb computer terminal.

dumb•ly, adv. 
dumb•ness, n. [uncountable]

WordReference Random House Unabridged Dictionary of American English © 2025

dumb  (dum), adj., -er, -est, v. 

1. lacking intelligence or good judgment;
   stupid;
   dull-witted.
2. lacking the power of speech (often offensive when applied to humans):
   a dumb animal.
3. temporarily unable to speak:
   dumb with astonishment.
4. refraining from any or much speech;
   silent.
5. made, done, etc., without speech.
6. lacking some usual property, characteristic, etc.
7. Show Business performed in pantomime;
   mimed.
8. Computing pertaining to the inability to do processing locally:
   A dumb terminal can input, output, and display data, but cannot process it.
   Cf. intelligent (def. 4).
9. [Naut.]
   • Naval Terms (of a barge) without means of propulsion.
   • Naval Terms (of any craft) without means of propulsion, steering, or signaling.

v. 

10. dumb down, to revise to appeal or be understandable to less intelligent people;
    lower the intellectual content of:
    to dumb down a textbook; the dumbing down of American movies.

• bef. 1000; Old English; cognate with Old Norse dumbr, Gothic dumbs, Old Saxon dumb, Old High German tump, German dumm

dumb′ly, adv. 
dumb′ness, n. 
Synonyms

• 2, 3. Dumb, mute, speechless, voiceless describe a condition in which speech is absent.
  Dumb was formerly used to refer to persons unable to speak; it is now used almost entirely of the inability of animals to speak:
  dumb beasts of the field.
  The term mute is applied to persons who, usually because of congenital deafness, have never learned to talk:
  With training most mutes learn to speak well enough to be understood.
  Either of the foregoing terms or speechless may describe a temporary inability to speak, caused by emotion, etc.:
  dumb with amazement; mute with terror; left speechless by surprise.
  Voiceless means literally having no voice, either from natural causes or from injury:
  Turtles are voiceless. A laryngectomy leaves a person voiceless until he or she has learned esophageal speech.

dumb, +v. 

1. dumb down, to revise to appeal or be understandable to less intelligent persons;
   lower the intellectual content of:
   to dumb down a textbook; the dumbing down of American movies.

Collins Concise English Dictionary © HarperCollins Publishers::

dumb / dʌm/ adjective

1. lacking the power of human speech: dumb animals
2. lacking the power to speak, either because of defects in the vocal organs or because of hereditary deafness
3. temporarily lacking or bereft of the power to speak: struck dumb
4. refraining from speech; uncommunicative
5. producing no sound; silent: a dumb piano
6. made, done, or performed without speech
7. slow to understand
8. foolish; stupid
9. (of an electronic device) not able to access the internet or function as a computer: a dumb phone

Etymology: Old English; related to Old Norse dumbr, Gothic dumbs, Old High German tump

ˈdumbly adverb

ˈdumbness noun