Word Origin & History
1660s, "process of suckling an infant," from Fr. lactation, from L. lactationem (nom. lactatio) "a suckling," from L. lactatus, pp. of lactare "suckle," from lac (gen. lactis) "milk," from PIE base *glact- (cf. Gk. gala, gen. galaktos "milk"). Meaning "process of secreting milk from the breasts" first
recorded 1857. M.Ir. lacht, Welsh llaeth "milk" are loan words from Latin.