Meaning

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

noun the highest level or degree attainable; the highest stage of development

noun a lofty peak

originFrom Middle English, borrowed from Old French pinacle, pinnacle, from Late Latin pinnāculum (“a peak, pinnacle”), from Latin pinna (“a pinnacle”); see pin. Doublet of panache.

Etymology from Wiktionary, CC BY-SA 3.0