1. lacking intelligence or good judgment; stupid; dull-witted.
2. lacking the power of speech (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. performed in pantomime; mimed.
8. Computers. pertaining to the inability to do processing locally: A dumb terminal can input, output, and display data, but cannot process it.Compare intelligent (def. 4).
9. Nautical. (of a barge) without means of propulsion. (of any craft) without means of propulsion, steering, or signaling.

I stand corrected (again)!