the world > movement > motion in a certain direction > downward motion > move downwards [verb (intransitive)] > plunge > plunge forward (2)
intransitive. To make a sudden or violent movement forward, esp. with a diving action; spec. (of a horse) to make such a movement with the head and…
intransitive. Of a person, animal, or vehicle: to move or progress like a pitching ship; to stagger or lurch, esp. with erratic forward movement.