Merriam-Webster Collegiate Dictionary - metric

 I. noun  Etymology: Greek metrike, from feminine of metrikos in meter, by measure, from metron measure — more at measure  Date: 1760  1. plural a part of prosody that deals with ~al structure  2. a standard of measurement no ~ exists that can be applied directly to happiness — Scientific Monthly  3. a mathematical function that associates a real nonnegative number analogous to distance with each pair of elements in a set such that the number is zero only if the two elements are identical, the number is the same regardless of the order in which the two elements are taken, and the number associated with one pair of elements plus that associated with one member of the pair and a third element is equal to or greater than the number associated with the other member of the pair and the third element  II. adjective  Etymology: French metrique, from metre meter  Date: 1864 of, relating to, or using the ~ system a ~ study  • ~ally adverb METRIC  or ~al  adjective combining form  1. of, employing, or obtained by (such) a meter galvanometric  2. of or relating to (such) an art, process, or science of measuring geometrical