/ Dictionary / Index C costal: Meaning and Definition of Find definitions for: cos•tal Pronunciation: (kos'tl, kôs'tl), [key] — adj. pertaining to the ribs or the upper sides of the body: costal nerves. pertaining to, involving, or situated near a costa. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: costal (Thesaurus) Costain Costa Mesa Related Content Daily Word Quiz: penchant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language