The Collaborative International Dictionary of English v.0.48:

indentured \indentured\ adj.
   Bound by contract to work for another for a specified period
   of time.

   Syn: apprenticed, articled, bound.
        [WordNet 1.5 +PJC]

The Collaborative International Dictionary of English v.0.48:

Indenture \In*den"ture\, v. t. [imp. & p. p. Indentured; p.
   pr. & vb. n. Indenturing.]
   [1913 Webster]
   1. To indent; to make hollows, notches, or wrinkles in; to
      furrow.
      [1913 Webster]

            Though age may creep on, and indenture the brow.
                                                  --Woty.
      [1913 Webster]

   2. To bind by indentures or written contract; as, to
      indenture an apprentice.
      [1913 Webster]

WordNet (r) 3.0 (2006):

indentured
    adj 1: bound by contract [syn: apprenticed, articled,
           bound, indentured]