Post-office

noun
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 initial capital letter) 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.
noun
1.
a building or room where postage stamps are sold and other postal business is conducted
noun
1.
a government department or authority in many countries responsible for postal services and often telecommunications
n.

1650s, “public department in charge of letter-carrying,” from post (n.3) + office. Meaning “building where postal business is carried on” is from 1650s. In slang or euphemistic sense of “a sexual game” it refers to an actual parlor game first attested early 1850s in which pretend “letters” were paid for by kisses.