The Collaborative International Dictionary of English v.0.48:

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 and
   curtsey.]
   [1913 Webster]

         The lady drops a courtesy in token of obedience, and
         the ceremony proceeds as usual.          --Golgsmith.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

curtsey \curt"sey\, curtsy \curt"sy\(k[^u]rt"s[y^]), n.
   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. Same as 2nd Courtesy, n..

   Syn: curtsy; courtesy.
        [1913 Webster + WordNet 1.5] curtsey

The Collaborative International Dictionary of English v.0.48:

curtsey \curtsey\, curtsy \curtsy\v. i.
   to perform a curtsy.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

curtsey
    n 1: bending the knees; a gesture of respect made by women [syn:
         curtsy, curtsey]
    v 1: bend the knees in a gesture of respectful greeting [syn:
         curtsy, curtsey]