law of definite composition: Meaning and Definition of

law' of def'inite composi'tion

Pronunciation: [key]
  1. the statement that in a pure compound the elements are always combined in fixed proportions by weight.
  2. the law that either a proposition or its denial must be true.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.