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No - the poster who mentioned the the original meaning of the word "dumb" meaning unable to speak is correct - but it meant that ove a hundred years ago...over time dumb started to be connected to meaning "dumb people" (non-speaking people) were unintelligent because they were unable to speak. This associate in words continued until the meaning of dumb no longer primarily meant unable to speak, but instead meant someone who was "stupid" or unintelligent.
We see this type of mutation of word meaning all the time ... just think of the word "cool" ... which used to primarily mean an indication of temperature - now the common usage of "cool" also means something that is "neat", "hip" etc.
Of course as the usage and meaning of words change we (people in general) have a responsibly to not only remind ourselves and others of the original meaning, but also correct improper connections, and culturally/socially/politically/morally offensive usage of the word when necessary. This is seen clearly the case of the word "dumb"