The Collaborative International Dictionary of English v.0.48:

Tsarina \Tsa*ri"na\, Tsaritsa \Tsa*rit"sa\, n. [Russ. tsaritsa.
   Cf. Czarina.]
   The title of the empress of Russia. See Czarina.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tsarina
    n 1: the wife or widow of a czar [syn: czarina, tsarina,
         tzarina, czaritza, tsaritsa]