Definition from Wiktionary, the free dictionary
See also pöstmȧster
postmaster (plural postmasters)
- the head of a post office
- the administrator of an electronic mail system
- (UK) A kind of scholar at Merton College, Oxford; portionist.
- (archaic) One who has charge of a station for the accommodation of travellers; one who supplies post horses.
Derived terms 
the head of a post office