The Collaborative International Dictionary of English v.0.48:

Castaway \Cast"a*way\, n.
   1. One who, or that which, is cast away or shipwrecked.
      [1913 Webster]

   2. One who is ruined; one who has made moral shipwreck; a
      reprobate.
      [1913 Webster]

            Lest . . . when I have preached to others, I myself
            should be a castaway.                 --1 Cor. ix.
                                                  27.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Castaway \Cast"a*way\, a.
   Of no value; rejected; useless.
   [1913 Webster]

WordNet (r) 3.0 (2006):

castaway
    n 1: a person who is rejected (from society or home) [syn:
         outcast, castaway, pariah, Ishmael]
    2: a shipwrecked person [syn: castaway, shipwreck survivor]