metric (adj.) Look up metric at
"pertaining to the system of measures based on the meter," 1855, from French métrique, from mèter (see meter (n.2)). In this sense, metrical is attested from 1797.
metric (n.) Look up metric at
"science of versification," 1760, from Greek he metrike "prosody," plural of metron "meter, a verse; that by which anything is measured; measure, length, size, limit, proportion" (from PIE root *me- (2) "to measure").