Source : Webster's Revised Unabridged Dictionary (1913)

Aboard \A*board"\, adv. [Pref. a- on, in + board.]
   On board; into or within a ship or boat; hence, into or
   within a railway car.

   2. Alongside; as, close aboard. Naut.:

   {To fall aboard of}, to strike a ship's side; to fall foul
      of.

   {To haul the tacks aboard}, to set the courses.

   {To keep the land aboard}, to hug the shore.

   {To lay (a ship) aboard}, to place one's own ship close
      alongside of (a ship) for fighting.