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. [1913 Webster]

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. [1913 Webster +PJC]

Source: The Collaborative International Dictionary of English v.0.48
 

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.

Source: Webster's Revised Unabridged Dictionary (1913)