/ Thesaurus / L Synonyms of law of constant proportion Find synonyms for: Noun1. law of constant proportion, law of definite proportions, law, law of natureusage: (chemistry) law stating that every pure substance always contains the same elements combined in the same proportions by weightWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: grimace Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language