acme, height, elevation, peak, pinnacle, summit, superlative, meridian, tiptop, top -- (the 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")
meridian, line of longitude -- (an imaginary great circle on the surface of the earth passing through the north and south poles at right angles to the equator; "all points on the same meridian have the same longitude")
Overview of adj meridian
The adj meridian has 2 senses
meridian -- (of or happening at noon; "meridian hour")
prime, meridian -- (being at the best stage of development; "our manhood's prime vigor"- Robert Browning)