Nouns

(n)extremum, peakthe most extreme possible amount or value“voltage peak”
(n)flower, prime, peak, heyday, bloom, blossom, efflorescence, flushthe period of greatest prosperity or productivity
(n)acme, height, elevation, peak, pinnacle, summit, superlative, meridian, tiptop, topthe highest level or degree attainable; the highest stage of development“his landscapes were deemed the acme of beauty”, “the artist's 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”
(n)peak, crown, crest, top, tip, summitthe top or extreme point of something (usually a mountain or hill)“the view from the peak was magnificent”, “they clambered to the tip of Monadnock”, “the region is a few molecules wide at the summit”
(n)point, tip, peaka V shape“the cannibal's teeth were filed to sharp points”
(n)vertex, peak, apex, acmethe highest point (of something)“at the peak of the pyramid”
(n)bill, peak, eyeshade, visor, vizora brim that projects to the front to shade the eyes“he pulled down the bill of his cap and trudged ahead”

Verbs

(v)top out, peakto reach the highest point; attain maximum intensity, activity“That wild, speculative spirit peaked in 1929”, “Bids for the painting topped out at $50 million”