The Collaborative International Dictionary of English v.0.48:

Metrology \Me*trol"o*gy\, n. [Gr. ? measure + -m['e]trologie.]
   The science of, or a system of, weights and measures; also, a
   treatise on the subject.
   [1913 Webster]

WordNet (r) 3.0 (2006):

metrology
    n 1: the scientific study of measurement