—n.
1 a measurable extent of any kind, as length, breadth, depth, area, and volume.
2 (in pl.) size, scope, extent.
3 an aspect or facet of a situation, problem, etc.
4 Algebra one of a number of unknown or variable quantities contained as factors in a product (x(3), x(2)y, xyz, are all of three dimensions).
5 Physics the product of mass, length, time, etc., raised to the appropriate power, in a derived physical quantity.
—v.tr. (usu. as dimensioned adj.) mark the dimensions on (a diagram etc.).
Derivatives:
dimensional adj. (also in comb.). dimensionless adj.
Etymology: ME f. OF f. L dimensio -onis (as DI-(2), metiri mensus measure)
Useful english dictionary. 2012.