pinnacle

n. 1 culmination or climax. 2 natural peak. 3 small ornamental turret crowning a buttress, roof, etc. [latin pinna *pin]

n. 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.