Is it farther or further?
"young woman," c.1300, probably from a Scandinavian source akin to Old Swedish løsk kona "unmarried woman," but also perhaps related to Old Norse löskr "idle, weak," West Frisian lask "light, thin." Liberman suggests Old Danish las "rag." "Slang words for 'rag' sometimes acquire the jocular meaning 'child' and especially 'girl.'" "Used now only of mean girls" [Johnson, who also has lasslorn "forsaken by his mistress"]. Scottish diminutive lassie first recorded 1725.