/ Dictionary / Index W western mountain ash: Meaning and Definition of Find definitions for: west'ern moun'tain ash' Pronunciation: [key] a mountain ash, Sorbus sitchensis, of western North America. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. westernmost Western Ocean Related Content Daily Word Quiz: sinister Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language