<p><strong>Noun</strong></p><ul><li>Mathematics. a number usually expressed in the form a/b.</li><li>a ratio of algebraic quantities similarly expressed.</li><li>Chemistry. (in a volatile mixture) a component whose range of boiling point temperatures allows it to be separated from other components by fractionation.</li><li>a part as distinct from the whole of anything; portion or section: The meeting started with a fraction of us present.</li><li>a very small part or segment of anything; minute portion: Only a fraction of the work was completed on time.</li><li>a very small amount; a little bit: It was only a fraction away from completion.</li><li>a piece broken off; fragment or bit.</li><li>the act of breaking.</li><li>Ecclesiastical. (in a Eucharistic service) the breaking of the Host.</li></ul><p><strong>Verb</strong></p><ul><li>(used with or without object) to divide or break into fractions, sections, factions, etc.: Dissension threatens to fraction the powerful union.</li></ul>