dialysis

noun pl. dialyses

1. Chem. any process in which the smaller dissolved molecules in a solution separate from the larger molecules by diffusing through a semipermeable membrane
2. Med. any of various procedures, usually performed on a regular basis on patients who have impaired kidney function, in which chemical dialysis is used to remove toxic waste, chemicals, etc. from the blood

Origin: L < Gr, separation, dissolution < dialyein, to separate, dissolve < dia-, apart + lyein, loose