/ Dictionary / Index M messenger RNA: Meaning and Definition of Find definitions for: messenger RNA Pronunciation: [key] a single-stranded molecule of RNA that is synthesized in the nucleus from a DNA template and then enters the cytoplasm, where its genetic code specifies the amino acid sequence for protein synthesis. Abbr.: mRNA Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. messenger Messenia Related Content Daily Word Quiz: philately Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language