Definitions for: Overboard

[adv] from on board a vessel into the water; "they dropped their garbage overboard"
[adv] to extremes; "he went overboard to please his in-laws"

Webster (1913) Definition: 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.