/ Dictionary / Index W wmk.: Meaning and Definition of Find definitions for: wmk. Pronunciation: [key] watermark. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. WMC WMO Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language