What does "astern" mean?

Astern: Behind a ship; in the rear. "A gale of wind right astern." De Foe. "Left this strait astern." Drake. To bake astern, to go stern foremost. -- To be astern of the reckoning, to be behind the position given by the reckoning. -- To drop astern, to fall or be left behind. -- To go astern, to go backward, as from the action of currents or winds.