This term was used long ago to describe a person who could not hear or speak. Using such a phrase today is considered quite rude, as being
deaf obviously has no relationship to a person's
intelligence. If a deaf child is deprived of
language and
education, they may never do very well as a member of society, but intelligence has nothing to do with the results of an
audiogram. Although
dumb used to mean "mute," it is also inaccurate when applied to deaf people in general as many are in fact able to speak.
See also deaf-mute.