Source : Webster's Revised Unabridged Dictionary (1913)

Farewell \Fare`well"\, interj. [Fare (thou, you) + well.]
   Go well; good-by; adieu; -- originally applied to a person
   departing, but by custom now applied both to those who depart
   and those who remain. It is often separated by the pronoun;
   as, fare you well; and is sometimes used as an expression of
   separation only; as, farewell the year; farewell, ye sweet
   groves; that is, I bid you farewell.

         So farewell hope, and with hope, farewell fear.
                                                  --Milton.

         Fare thee well! and if forever, Still forever fare thee
         well.                                    --Byron.

   Note: The primary accent is sometimes placed on the first
         syllable, especially in poetry.

Farewell \Fare`well"\, n.
   1. A wish of happiness or welfare at parting; the parting
      compliment; a good-by; adieu.

   2. Act of departure; leave-taking; a last look at, or
      reference to something.

            And takes her farewell of the glorious sun. --Shak.

            Before I take my farewell of the subject. --Addison.

Farewell \Fare"well`\, a.
   Parting; valedictory; final; as, a farewell discourse; his
   farewell bow.

         Leans in his spear to take his farewell view.
                                                  --Tickell.

   {Farewell rock} (Mining), the Millstone grit; -- so called
      because no coal is found worth working below this stratum.
      It is used for hearths of furnaces, having power to resist
      intense heat. --Ure.

Source : WordNet®

farewell
     n 1: an acknowledgment or expression of goodwill at parting [syn:
           {word of farewell}]
     2: the act of departing politely; "he disliked long farewells";
        "he took his leave"; "parting is such sweet sorrow" [syn:
        {leave}, {leave-taking}, {parting}]