The comprehensive definition of highest. Includes pronunciation, synonyms, etymology, and usage examples to help you master this word. Mount Everest, known as the highest mountain on Earth, stands at 29,029 feet (8,848 meters) above sea level. The term 'absolute height' measures how far something is from the center of the Earth, not just sea level. Mauna Kea (4,207 m (13,802 ft) above sea level) is the world 's tallest mountain and volcano, rising about 10,203 m (33,474 ft) from the Pacific Ocean floor. Adjective highest superlative form of high: most high Synonyms: maximum, ultimate, utmost; see also Thesaurus: extreme top note - The highest in a piece of music or in a singer's vocal range. paramount, tantamount - Paramount means primary, top, and tantamount means equivalent to, same as ; paramount first meant highest in jurisdiction. high /haɪ/ adj. andadv., -er, -est, n. lofty: a high wall. (of things) having a specified height: The tree is 20 feet high. elevated: a high ledge. greater than or going beyond the usual degree, measure, or amount: high speed; high prices. good: high moral principles. The meaning of HIGH is rising or extending upward a great distance or a distance greater than others of its kind : taller than average, usual, or expected. How to use high in a sentence. Synonym Discussion of High.