aphetic
/əˈfɛtɪk/Definitions
1. adjective
not speaking or not speaking much; mute or silent
“The aphetic child stared silently at her teacher.”
2. noun
A term used in some phonetic systems to denote a sound or silence that is not represented by any written symbol.
“In some phonetic transcriptions, the term ‘aphetic’ may be used to describe a sound or silence that is not represented by any written symbol.”