/ Dictionary / Index F fungus gnat: Meaning and Definition of Find definitions for: fun'gus gnat" Pronunciation: [key] any of several mosquitolike insects of the family Mycetophilidae, the larvae of which feed on fungi or decaying vegetation. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. fungus bug fungus root 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