/ Dictionary / Index M micronucleus: Meaning and Definition of Find definitions for: mi•cro•nu•cle•us Pronunciation: (mī"krō-n'klē-us, -ny'-), [key] — pl. -cle•i the smaller of the two types of nuclei occurring in ciliate protozoans. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. micronucleate micronutrient Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language