A standard for expressing the amount of a property.
Units serve as the basic technical discriminator between property values in preference to dimensions for two reasons:
1) Dimensional concepts established by most international conventions address little beyond the physical sciences.
2) The established conventions do not uniformly distinguish between affine concepts and positional concepts1.
Don’t misunderstand me: I am a strong proponent of using the physical systems of dimensional specification and analysis for physical problems. I just have to work problems other than mere physical ones, so cannot advocate their exclusive usage.
Footnotes- For example, a “foot” of displacement is the same as a “foot” of length, leading to the dimensional confounding between torque and work.[↩]