The word weight has many uses in mathematics. It can refer to a function (also called a weighting function or weighting function) used to normalize orthogonal functions. It can also be used to indicate one of a set of a multiplicative constants placed in front of terms in a moving average, Newton-Cotes formulas, edge or vertex of a graph or tree, etc. It also refers to the power in the multiplicative factor defining a modular form.

The weight of a tree at a point is the maximum number of edges in any branch at (Harary 1994, p. 35).