Source : Webster's Revised Unabridged Dictionary (1913)

Phimosis \Phi*mo"sis\, n. [NL., fr. Gr. ? a muzzling, fr. ?
   muzzle.] (Med.)
   A condition of the penis in which the prepuce can not be
   drawn back so as to uncover the glans penis.

Source : WordNet®

phimosis
     n : an abnormal tightness of the foreskin preventing retraction
         over the glans