out of curl
obsolete Of hair, straight and limp; no longer curly. After spending so much time on her hair, Mary was worried that it would come out of curl if she stepped outside into the storm.
out of curl
lacking energy. British This is an early 20th-century expression based on the idea that curly hair has vitality (as in ‘bouncy curls’). Therefore, hair which has become limp or out of curl may be thought to indicate listlessness or enervation.