In mathematics, a number indicating the fewest coordinates necessary to identify a point in a geometric space; more generally, a number indicating a measurement of length (see length, area, and volume ).
One-dimensional space can be represented by a numbered line, on which a single number identifies a point. In two-dimensional space, a coordinate system may be superimposed, requiring only two numbers to identify a point. Three numbers suffice in three-dimensional space, and so on.