overboard

As a verb overturn

is to turn over, capsize or upset (something).

As an adjective overboard is

outside of a boat, in the water.

As an adverb overboard is

over the edge; especially, off or outside of a boat.

As an adjective overboard

is outside of a boat, in the water.

As an adverb overboard

is over the edge; especially, off or outside of a boat.

As a noun jettison is

collectively, items that have been or are about to be ejected from a boat or balloon.

As a verb jettison is

to eject from a boat, submarine, aircraft, spaceship or hot-air balloon, so as to lighten the load.

As an adjective overboard

is outside of a boat, in the water.

As an adverb overboard

is over the edge; especially, off or outside of a boat.

As a verb jettisoned is

(jettison).

As a verb offboard

is to alight, especially from public transit or an aircraft.

As an adjective overboard is

outside of a boat, in the water.

As an adverb overboard is

over the edge; especially, off or outside of a boat.

As adjectives the difference between outboard and overboard

is that outboard is situated outside the hull of a vessel while overboard is outside of a boat, in the water.

As a noun outboard

is an outboard motor.

As an adverb overboard is

over the edge; especially, off or outside of a boat.

As adjectives the difference between onboard and overboard

is that onboard is carried or used on or in a vehicle or vessel while overboard is outside of a boat, in the water.

As adverbs the difference between onboard and overboard

is that onboard is on or in a vehicle or vessel; aboard; on board while overboard is over the edge; especially, off or outside of a boat.

As a noun hoverboard

is a levitating board that can be ridden in the manner of a surfboard or skateboard.

As an adjective overboard is

outside of a boat, in the water.

As an adverb overboard is

over the edge; especially, off or outside of a boat.