Source : Webster's Revised Unabridged Dictionary (1913)

Oblige \O*blige"\, v. t. [imp. & p. p. {Obliged}; p. pr. & vb.
   n. {Obliging}.] [OF. obligier, F. obliger, L. obligare; ob
   (see {Ob-}) + ligare to bind. See {Ligament}, and cf.
   {Obligate}.]
   1. To attach, as by a bond. [Obs.]

            He had obliged all the senators and magistrates
            firmly to himself.                    --Bacon.

   2. To constrain by physical, moral, or legal force; to put
      under obligation to do or forbear something.

            The obliging power of the law is neither founded in,
            nor to be measured by, the rewards and punishments
            annexed to it.                        --South.

            Religion obliges men to the practice of those
            virtues which conduce to the preservation of our
            health.                               --Tillotson.

   3. To bind by some favor rendered; to place under a debt;
      hence, to do a favor to; to please; to gratify; to
      accommodate.

            Thus man, by his own strength, to heaven would soar,
            And would not be obliged to God for more. --Dryden.

            The gates before it are brass, and the whole much
            obliged to Pope Urban VIII.           --Evelyn.

            I shall be more obliged to you than I can express.
                                                  --Mrs. E.
                                                  Montagu.

Source : WordNet®

obliged
     adj : under a moral obligation to do something [syn: {duty-bound(p)},
            {obliged(p)}]