sis lit., a muzzling, equiv. to phīmō-, verbid s. of phīmoûn to muzzle + -sis -sis 
phimosis phi·mo·sis (fī-mō'sĭs, fĭ-)
n. pl. phi·mo·ses (-sēz)
An abnormal constriction of the foreskin that prevents it from being drawn back to uncover the glans penis.