/ Dictionary / Index C coastal plain: Meaning and Definition of Find definitions for: coast'al plain' Pronunciation: [key] a plain extending along a coast. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. coastal coast artillery Related Content Daily Word Quiz: digression Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language