tailspin
noun uk/ˈteɪlˌspɪn/ us/ˈteɪlˌspɪn/
[ C usually singular ]（飞机的）尾旋，尾螺旋
a situation in which a plane turns round and round as it falls quickly towards the ground
[ S ]失控状态，混乱
a situation in which something starts to fail or lose value and gets more and more out of control
Share prices went into a tailspin when the CEO resigned. 首席执行官辞职后股价直线下跌。