Learner's definition of TAILSPIN
1 : a condition in which an airplane is falling rapidly while turning around and around 2 : a state in which something quickly becomes much worse
Stock prices are in a tailspin.
The team went into a tailspin and lost six straight games.
The news of his death sent her into a tailspin. [=caused her to become very unhappy, to lose control of her life, etc.]