IPA: /pərˈmɪtər/
KK: /pərˈmɪtər/
A person who allows something to happen or gives permission for something.
The permitter granted access to the restricted area after reviewing the request.
Permitters are derived from 'permit' (from Latin 'permittere', meaning to allow or let go) and the suffix '-er' (meaning a person who). Thus, a 'permitter' is a person who allows or grants permission.
Think of someone who 'allows' ('permittere') something to happen — that's what a permitter does.