Definition of pinnacle

• (architecture) a slender upright spire at the top of a buttress of tower
• the highest level or degree attainable; the highest stage of development; "his landscapes were deemed the acme of beauty"; "the artists gifts are at their acme"; "at the height of her career"; "the peak of perfection"; "summer was at its peak"; "...catapulted Einstein to the pinnacle of fame"; "the summit of his ambition"; "so many highest superlatives achieved by man"; "at the top of his profession"
• a lofty peak