The Collaborative International Dictionary
To throw overboard
Overboard \O"ver*board`\, adv. Over the side of a ship; hence, from on board of a ship, into the water; as, to fall overboard.
To throw overboard, to discard; to abandon, as a dependent or friend.
To go overboard, to go to an extreme; to overdo; as, he went overboard at the buffet and got an upset stomach.