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.