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.