A decrease in positive valence or an increase in negative valence by the gaining of electrons. in Chemistry

The first meiotic division, in which the chromosome number is reduced. Also called reduction division. in  Biology

 The canceling of common factors in the numerator and denominator of a maths
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Reduction can be said when :-

i) Electron is gained
ii)Addition of hydrogen atom (or electropositive atom)
iii)Loss of oxygen atom (or electronegative atom)

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