noun
(aviation) The rapid, uncontrollable descent of an aircraft in a steep spiral.
(figuratively) A severe mental or emotional collapse; emotional breakdown.
(figuratively) Any sharp, sustained, often uncontrollable descent or decline.
verb
Of an aircraft: to go into a rapid, uncontrollable descent in a steep spiral.
(figurative) To go into a sharp, sustained, often uncontrollable descent or decline.