›mathematicsa number that results from dividing one whole number (= a number with no part of a number after it) by another: 1/4 and 0.25 are different ways of representing the same fraction.›A fraction is also a very small part or amount of something: Counterfeits are sold at a fraction of the cost of the genuine articles.Juries often hear only a fraction of the story.fractionaladjmathematics