Mathematics .

a property of space; extension in a given direction

A straight line has one dimension, a parallelogram has two dimensions, and a parallelepiped has three dimensions.

the generalization of this property to spaces with curvilinear extension, as the surface of a sphere.

the generalization of this property to vector spaces and to Hilbert space.

the generalization of this property to fractals, which can have dimensions that are noninteger real numbers.

extension in time

Space-time has three dimensions of space and one of time.

Usually, dimensions.

measurement in length, width, and thickness.

scope; importance

the dimensions of a problem.

unit ( def. 6 ) .

magnitude; size

Matter has dimension.

Topology .

a magnitude that, independently or in conjunction with other such magnitudes, serves to define the location of an element within a given set, as of a point on a line, an object in a space, or an event in space-time.

the number of elements in a finite basis of a given vector space.

Physics . any of a set of basic kinds of quantity, as mass, length, and time, in terms of which all other kinds of quantity can be expressed; usually denoted by capital letters, with appropriate exponents, placed in brackets

The dimensions of velocity are [[[LT]] ?1 Compare dimensional analysis

dimensions, Informal . the measurements of a woman's bust, waist, and hips, in that order

The chorus girl's dimensions were 38-24-36.

dimension lumber.

to shape or fashion to the desired dimensions

Dimension the shelves so that they fit securely into the cabinet.

to indicate the dimensions of an item, area, etc., on (a sketch or drawing).