Mutism
The inability or unwillingness to speak.
A person who is mute cannot or does not care to talk.
Someone who was mute was said to be dumb, not in the sense of being stupid, but in the sense of being devoid of the power of speech.
The term 'mutism' is specifically applied to people who, due to profound congenital (or early) deafness, are unable to use articulate language and so are affected by deaf-mutism.
The word 'mutism' comes from the Latin 'mutus' meaning unable to speak