Source : Webster's Revised Unabridged Dictionary (1913)

Courtesy \Courte"sy\ (k[^u]rt"s[y^]), n. [See the preceding
   word.]
   An act of civility, respect, or reverence, made by women,
   consisting of a slight depression or dropping of the body,
   with bending of the knees. [Written also {curtsy}.]

         The lady drops a courtesy in token of obedience, and
         the ceremony proceeds as usual.          --Golgsmith.

Courtesy \Courte"sy\, v. i. [imp. & p. p. {Courtesied}
   (-s[i^]d); p. pr. & vb. n. {Courtesying}.]
   To make a respectful salutation or movement of respect; esp.
   (with reference to women), to bow the body slightly, with
   bending of the knes.

Courtesy \Cour"te*sy\ (k?r"t?-s?), n.; pl. {Courtesies} (-s?z).
   [OE. cortaisie, corteisie, courtesie, OF. curteisie,
   cortoisie, OF. curteisie, cortoisie, F. courtoisie, fr.
   curteis, corteis. See {Courteous}.]
   1. Politeness; civility; urbanity; courtliness.

            And trust thy honest-offered courtesy, With oft is
            sooner found in lowly sheds, With smoky rafters,
            than in tapestry walls And courts of princes, where
            it first was named, And yet is most pretended.
                                                  --Milton.

            Pardon me, Messer Claudio, if once more I use the
            ancient courtesies of speech.         --Longfellow.

   2. An act of civility or respect; an act of kindness or favor
      performed with politeness.

            My lord, for your many courtesies I thank you.
                                                  --Shak.

   3. Favor or indulgence, as distinguished from right; as, a
      title given one by courtesy.

   {Courtesy title}, a title assumed by a person, or popularly
      conceded to him, to which he has no valid claim; as, the
      courtesy title of Lord prefixed to the names of the
      younger sons of noblemen.

   Syn: Politiness; urbanity; civility; complaisance;
        affability; courteousness; elegance; refinement;
        courtliness; good breeding. See {Politeness}.

Courtesy \Courte"sy\, v. t.
   To treat with civility. [Obs.]

Source : WordNet®

courtesy
     n 1: a courteous or respectful or considerate act
     2: a courteous or respectful or considerate remark
     3: a courteous manner [syn: {good manners}] [ant: {discourtesy}]