Merriam-Webster Collegiate Dictionary - summit

 I. noun  Etymology: Middle English somete, from Anglo-French sumet, diminutive of sum top, from Latin summum, neuter of summus highest — more at sum  Date: 15th century  1. top, apex; especially the highest point ; peak  2. the topmost level attainable the ~ of human fame  3.  a. the highest level of officials; especially the diplomatic level of heads of government  b. a conference of highest-level officials (as heads of government) an economic ~ Synonyms:  ~, peak, pinnacle, climax, apex, acme, culmination mean the highest point attained or attainable. ~ implies the topmost level attainable at the ~ of the Victorian social scene. peak suggests the highest among other high points an artist working at the peak of her powers. pinnacle suggests a dizzying and often insecure height the pinnacle of worldly success. climax implies the highest point in an ascending series the war was the climax to a series of hostile actions. apex implies the point where all ascending lines converge the apex of Dutch culture. acme implies a level of quality representing the perfection of a thing a statue that was once deemed the acme of beauty. culmination suggests the outcome of a growth or development representing an attained objective the culmination of years of effort.  II. intransitive verb  Date: 1972  1. to participate in a ~ conference  2. to climb to the ~ ~ed on May 29