/ Dictionary / Index A all-or-none law: Meaning and Definition of Find definitions for: all'-or-none' law" Pronunciation: (ôl'ur-nun'), [key] — Physiol. Physiol. the principle that under given conditions the response of a nerve or muscle fiber to a stimulus at any strength above the threshold is the same: the muscle or nerve responds completely or not at all. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. allopurinol all-or-nothing Related Content Daily Word Quiz: agitated Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language