Selective mutism (SM) is an anxiety disorder in which a person who is normally capable of speech does not speak in specific situations or to specific people. Selective mutism usually co-exists with shyness or social anxiety. Children with selective mutism stay silent even when the consequences of their silence include shame, social ostracism or ev... Found on http://en.wikipedia.org/wiki/Selective_mutism
selective mutism (SM) Seemingly incongruous behavior in which someone exhibits a ready flow of speech in private, but silence in public. More silence-content words at these links: silen- and tacit-. Found on http://www.wordinfo.info/words/index/info/view_unit/3332/