/ Dictionary / Index E endonuclease: Meaning and Definition of Find definitions for: en•do•nu•cle•ase Pronunciation: (en"dō-n'klē-ās", -āz", -ny'-), [key] — n. Biochem. any of a group of enzymes that degrade DNA or RNA molecules by breaking linkages within the polynucleotide chains. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: endonuclease (Thesaurus) endomyocarditis endoparasite Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language