Pinnacle

An architectural member, upright, and generally ending in a small spire, -- used to finish a buttress, to constitute a part in a proportion, as where pinnacles flank a gable or spire, and the like. Pinnacles may be considered primarily as added weight, where it is necessary to resist the thrust of an arch, etc.

Anything resembling a pinnacle; a lofty peak; a pointed summit.

To build or furnish with a pinnacle or pinnacles.

(architecture) a slender upright spire at the top of a buttress or tower