Quiz: Remember the definition of mal de mer?
Old English liðe "soft, mild, gentle, meek," from Proto-Germanic *linthja- (cf. Old Saxon lithi "soft, mild, gentle," Old High German lindi, German lind, Old Norse linr, with characteristic loss of "n" before "th" in English), from PIE root *lent- "flexible" (cf. Latin lentus "flexible, pliant, slow," Sanskrit lithi). In Middle English, used of the weather. Current sense of "easily flexible" is from c.1300. Related: Litheness.