lithe (adj.) Look up lithe at Dictionary.com
Old English liðe "soft, mild, gentle, meek," from Proto-Germanic *linthja- (source also of 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" (source also of 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. Old and Middle English had the related verb lin "to cease doing (something)," also used of the wind dying down.