A compound fraction is a mathematical term which refers to a fraction that contains one or more other fractions in either the numerator or the denominator. Some synonyms for compound fraction include complex fraction, mixed fraction, fractional expression, and fraction within a fraction. A complex fraction is a compound fraction in which the numerator and/or denominator contains one or more fractions and may also contain variables. A mixed fraction is a compound fraction in which the part before the fraction is a whole number and the part after the fraction is a proper fraction. A fractional expression is a compound fraction in which either the numerator or the denominator is an algebraic expression.