1. (to cause) to become weak and dry and decay: "Grass had withered in the fields."2 Slowly disappear, lose importance or become weaker: "This country is in danger of allowing its industrial base to wither away."
If a flower or plant withers, it dries up and dies. The flowers in Isabel's room had withered. if plants wither, they become drier and smaller and start to die (Probably from weather )
If someone or something withers, they become very weak. When he went into retirement, he visibly withered Industries unable to modernise have been left to wither. Wither away means the same as wither. To see my body literally wither away before my eyes was exasperating