- The act or process of reducing.
- The result of reducing: a reduction in absenteeism.
- The amount by which something is lessened or diminished: a reduction of 12 percent in violent crime.
- Biology The first meiotic division, in which the chromosome number is reduced. Also called reduction division.
- Chemistry A decrease in positive valence or an increase in negative valence by the gaining of electrons.
- Chemistry A reaction in which hydrogen is combined with a compound.
- Chemistry A reaction in which oxygen is removed from a compound.
- Mathematics The canceling of common factors in the numerator and denominator of a fraction.
- Mathematics The converting of a fraction to its decimal equivalent.
- Mathematics The converting of an expression or equation to its simplest form.