/ Dictionary / Index C certified mail: Meaning and Definition of Find definitions for: cer'tified mail' Pronunciation: [key] uninsured first-class mail requiring proof of delivery. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. certified check certified milk Related Content Daily Word Quiz: laudable Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language