/ Dictionary / Index M Montes Apenninus: Meaning and Definition of Find definitions for: Mon•tes Ap•en•ni•nus Pronunciation: (mon'tus ap"u-nī'nus), [key] a mountain range in the first and second quadrants of the visible face of the moon, forming the SE border of Mare Imbrium: about 600 miles (970 km) long. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Monterrey Montes Claros Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language