The Collaborative International Dictionary of English v.0.48:

Adopt \A*dopt"\, v. t. [imp. & p. p. Adopted; p. pr. & vb. n.
   Adopting.] [L. adoptare; ad + optare to choose, desire: cf.
   F. adopter. See Option.]
   1. To take by choice into relationship, as, child, heir,
      friend, citizen, etc.; esp. to take voluntarily (a child
      of other parents) to be in the place of, or as, one's own
      child.
      [1913 Webster]

   2. To take or receive as one's own what is not so naturally;
      to select and take or approve; as, to adopt the view or
      policy of another; these resolutions were adopted.
      [1913 Webster]

WordNet (r) 3.0 (2006):

adopt
    v 1: choose and follow; as of theories, ideas, policies,
         strategies or plans; "She followed the feminist movement";
         "The candidate espouses Republican ideals" [syn: adopt,
         follow, espouse]
    2: take up and practice as one's own [syn: adopt, borrow,
       take over, take up]
    3: take on titles, offices, duties, responsibilities; "When will
       the new President assume office?" [syn: assume, adopt,
       take on, take over]
    4: take on a certain form, attribute, or aspect; "His voice took
       on a sad tone"; "The story took a new turn"; "he adopted an
       air of superiority"; "She assumed strange manners"; "The gods
       assume human or animal form in these fables" [syn: assume,
       acquire, adopt, take on, take]
    5: take into one's family; "They adopted two children from
       Nicaragua" [syn: adopt, take in]
    6: put into dramatic form; "adopt a book for a screenplay" [syn:
       dramatize, dramatise, adopt]
    7: take up the cause, ideology, practice, method, of someone and
       use it as one's own; "She embraced Catholicism"; "They
       adopted the Jewish faith" [syn: espouse, embrace,
       adopt, sweep up]