/ Dictionary / Index A atrial natriuretic factor: Meaning and Definition of Find definitions for: a'trial na'triuret'ic fac"tor Pronunciation: [key] any of several peptide hormones that are released by the atria of the heart in response to an abnormal increase in blood volume and that modulate blood pressure and the excretion of sodium, potassium, and water. Abbr: ANF&hasp; Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Atreus atrichia Related Content Daily Word Quiz: lunar Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language