adj. dumb·er, dumb·est
a. Lacking the power of speech. Used of animals and inanimate objects.
b. Offensive Incapable of using speech; mute. Used of humans. See Usage Note at mute.
2. Temporarily speechless, as with shock or fear: I was dumb with disbelief.
3. Unwilling to speak; taciturn.
4. Not expressed or articulated in sounds or words: dumb resentment.
5. Nautical Not self-propelling.
6. Conspicuously unintelligent; stupid: dumb officials; a dumb decision.
7. Unintentional; haphazard: dumb luck.
tr.v. dumbed, dumb·ing, dumbsPhrasal Verb:
To make silent or dumb.
dumb down (or up)
Slang To rewrite for a less educated or less sophisticated audience.
[Middle English, from Old English.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.