/ Dictionary / Index F filt.: Meaning and Definition of Find definitions for: filt. Pronunciation: [key] (in prescriptions) filter. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. fils filter Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language