The Probert Encyclopaedia of Architecture

SPIRE

In architecture a spire is the name given to the roof of a tower when of a pyramidal form and high in proportion to its width. The name is also given to the pyramidal or aspiring termination of a tower which can not be said to have a roof, such as that of Strasburg cathedral; and to the tapering part of a steeple, or the steeple itself.
Research Spire