Source : Webster's Revised Unabridged Dictionary (1913)

Vaginismus \Vag`i*nis"mus\, n. [NL.] (Med.)
   A painful spasmodic contraction of the vagina, often
   rendering copulation impossible.

Source : WordNet®

vaginismus
     n : muscular contraction that causes the vagina to close;
         usually an anxiety reaction before coitus or pelvic
         examination