Source : Webster's Revised Unabridged Dictionary (1913)

Astern \A*stern"\, adv. [Pref. a- + stern.] (Naut.)
   1. In or at the hinder part of a ship; toward the hinder
      part, or stern; backward; as, to go astern.

   2. 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.

Source : WordNet®

astern
     adv 1: stern foremost or backward; "the steamer went astern at half
            speed"
     2: at or near or toward the stern of a ship or tail of an
        airplane; "stow the luggage aft"; "ships with square sails
        sail fairly efficiently with the wind abaft"; "the captain
        looked astern to see what the fuss was about" [syn: {aft},
         {abaft}] [ant: {fore}]
     3: (of a ship or an airplane) behind; "we dropped her astern on
        the end of a seven-inch manilla, and she laid comfortably
        on the ebb tide"