n. & v.
--n.
1. the culmination or climax (of endeavour, success, etc.).
2 a natural peak.
3 a small ornamental turret usu. ending in a pyramid or cone, crowning a buttress, roof, etc.
--v.tr.
1. set on or as if on a pinnacle.
2 form the pinnacle of.
3 provide with pinnacles.
Etymology: ME pinacle f. OF pin(n)acle f. LL pinnaculum f. pinna wing, point (as PIN, -CULE)