me·trol·o·gy 
(mĕ-trŏlə-jē)
(mĕ-trŏlə-jē)n. pl. me·trol·o·gies
1. The science that deals with measurement.
2. A system of measurement.
[French métrologie, from Greek metrologiā, theory of ratios : metron, measure; see mē-2 in the Appendix of Indo-European roots + -logiā, -logy.]
met′ro·logi·cal (mĕt′rə-lŏjĭ-kəl) adj.
met′ro·logi·cal·ly adv.
me·trolo·gist n.