The witch was shriveling and growing smaller every moment.
女巫每时每刻都在萎缩、变小。
英语百科
Shrivelling
Shrivelling is a natural phenomenon where an object, with an attached sub-elastic covering, has its interior volume reduced in some way. The covering, which cannot contract any further, is then obliged to wrinkle and buckle, in order to preserve surface area while containing the lesser volume.