The Collaborative International Dictionary of English v.0.48:

Pay \Pay\, v. t. [imp. & p. p. Paid (p[=a]d); p. pr. & vb. n.
   Paying.] [OE. paien, F. payer, fr. L. pacare to pacify,
   appease, fr. pax, pacis, peace. See Peace.]
   1. To satisfy, or content; specifically, to satisfy (another
      person) for service rendered, property delivered, etc.; to
      discharge one's obligation to; to make due return to; to
      compensate; to remunerate; to recompense; to requite; as,
      to pay workmen or servants.
      [1913 Webster]

            May no penny ale them pay [i. e., satisfy]. --P.
                                                  Plowman.
      [1913 Webster]

            [She] pays me with disdain.           --Dryden.
      [1913 Webster]

   2. Hence, figuratively: To compensate justly; to requite
      according to merit; to reward; to punish; to retort or
      retaliate upon.
      [1913 Webster]

            For which, or pay me quickly, or I'll pay you. --B.
                                                  Jonson.
      [1913 Webster]

   3. To discharge, as a debt, demand, or obligation, by giving
      or doing what is due or required; to deliver the amount or
      value of to the person to whom it is owing; to discharge a
      debt by delivering (money owed). "Pay me that thou owest."
      --Matt. xviii. 28.
      [1913 Webster]

            Have patience with me, and I will pay thee all.
                                                  --Matt. xviii.
                                                  26.
      [1913 Webster]

            If they pay this tax, they starve.    --Tennyson.
      [1913 Webster]

   4. To discharge or fulfill, as a duy; to perform or render
      duty, as that which has been promised.
      [1913 Webster]

            This day have I paid my vows.         --Prov. vii.
                                                  14.
      [1913 Webster]

   5. To give or offer, without an implied obligation; as, to
      pay attention; to pay a visit.
      [1913 Webster]

            Not paying me a welcome.              --Shak.
      [1913 Webster]

   To pay off.
      (a) To make compensation to and discharge; as, to pay off
          the crew of a ship.
      (b) To allow (a thread, cord, etc.) to run off; to unwind.
      (c) to bribe.

   To pay one's duty, to render homage, as to a sovereign or
      other superior.

   To pay out (Naut.), to pass out; hence, to slacken; to
      allow to run out; as, to pay out more cable. See under
      Cable.

   To pay the piper, to bear the cost, expense, or trouble.
      [Colloq.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Piper \Pip"er\, n.
   1. (Mus.) One who plays on a pipe, or the like, esp. on a
      bagpipe. "The hereditary piper and his sons." --Macaulay.
      [1913 Webster]

   2. (Zool.)
      (a) A common European gurnard (Trigla lyra), having a
          large head, with prominent nasal projection, and with
          large, sharp, opercular spines.
      (b) A sea urchin (Goniocidaris hystrix) having very long
          spines, native of both the American and European
          coasts.
          [1913 Webster]

   To pay the piper, to bear the cost, expense, or trouble.
      [1913 Webster]