nosedive

A very steep dive of an aircraft.

A sudden, swift drop or plunge.

To drop with the nose or front first, as of an airplane.

A headfirst fall or jump.

A rapid fall in price or value.

To dive down in a steep angle.

To perform a rapid fall in price or value.

a steep nose-down descent by an aircraft

a sudden sharp drop or rapid decline

plunge nose first; drop with the nose or front first, of aircraft