1. an office or station of a government postal system at which mail is received and sorted, from which it is dispatched and distributed, and at which stamps are sold or other services rendered.
2. (often cap.) the department of a government charged with the transportation of mail.
3. a game in which one player is designated “postmaster” or “postmistress” and calls another player of the opposite sex into an adjoining room, ostensibly to receive a letter but actually to receive a kiss.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.