Noun
An emergency maneuver by a submarine in which it suddenly descends, especially to considerable depth, usually in order to escape an attack or avoid a collision.
A rapid descent by a person or thing, ending in a violent collision.
Three quarters of a front somersault, beginning on the feet and landing on the back.
Verb
To perform a crash dive.
To cause (a submarine) to perform a crash dive.
To rapidly descend, intentionally or accidentally, in a manner that ends in a violent collision.
To rapidly descend, in a manner that ends in a violent collision with (something).
To cause (something) to descend rapidly, in a manner that ends in a violent collision.