noun A tall, narrow structure (significantly taller than it is wide, either standing alone or forming part of a larger structure.
an observation tower, an isolated watch tower, a church tower, conning tower
noun A very tall open-framed structure on which communications devices are installed.
signal tower, radio tower, cell tower
noun A similarly framed structure with a platform or enclosed area on top.
observation tower, watch tower
noun A control tower.
noun A skyscraper.
The Sears Tower
noun An item of various kinds, such as a computer case, that is higher than it is wide.
noun A strong refuge; a defence.
noun Each of a set of information technology concerns within a business, which are treated separately so that they can be handled by different providers.