Real Dictionary

office
countable noun: An office is a department of an organization, especially the government, where people deal with a particular kind of administrative work.
countable noun: An office is a room or a part of a building where people work sitting at desks.
countable noun: An office is a small building or room where people can go for information, tickets, or a service of some kind.

office in American English
something performed or intended to be performed for another; (specified kind of) service
noun: a room, set of rooms, or building where the business of a commercial or industrial organization or of a professional person is conducted

office in British English
noun: a room or set of rooms in which business, professional duties, clerical work, etc, are carried out