What does dialysis mean?
Dialysis refers to a medical treatment that performs the work of healthy kidneys: it removes waste products, excess salts, and surplus fluid from the bloodstream when the body's own renal system can no longer cope. Most commonly associated with kidney failure, dialysis is typically administered either as hemodialysis, where blood is circulated through an external filtering machine, or as peritoneal dialysis, which uses the lining of the abdomen as a natural filter. Patients with end-stage renal disease may undergo dialysis several times weekly, often for years, while awaiting a transplant. Beyond medicine, the term also describes a laboratory technique in chemistry, in which small molecules diffuse across a semipermeable membrane to be separated from larger ones. Derived from Greek roots meaning 'to dissolve apart,' dialysis carries a serious, clinical register, and its use signals life-sustaining intervention in contexts of chronic illness.
nounA medical procedure that removes waste products, excess fluid, and toxins from the blood when the kidneys are unable to do so; it also denotes the underlying chemical process in which small dissolved particles separate from larger ones by diffusing through a semipermeable membrane.
- Medicine: a treatment that artificially removes waste products and excess fluid from the blood of patients whose kidneys are not functioning properly.
- Chemistry: the separation of smaller dissolved particles from larger ones by diffusion through a semipermeable membrane.
"After her kidneys failed, she began dialysis three times a week at the regional clinic."
"He has been on dialysis since his kidneys stopped functioning two years ago."
"In the laboratory, the protein solution was purified by dialysis against a buffer overnight."
The plural follows the Greek-style '-es' ending (pronounced /daɪˈælɪsiːz/) but is uncommon; 'dialysis' is usually treated as an uncountable noun even when multiple sessions occur.
"She underwent three dialyses per week during her first month of treatment."
The word 'dialysis' comes from the Greek for 'dissolving apart' — a fitting name for a process that literally separates life-sustaining substances from deadly waste.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dialysis
Dialysis derives from the Greek 'dialysis', meaning 'a dissolving' or 'separation', formed from 'dia-' (through or apart) and 'lysis' (loosening or dissolution). The term was adopted into English in the 19th century, initially within chemistry to describe diffusion-based separation before becoming firmly established in medicine as artificial kidney treatment developed in the early 20th century. It shares its root with related words such as analysis, paralysis, catalysis, and electrolysis.
How dialysis is actually used
Dialysis is a formal and technical term, used primarily in medical and scientific contexts. It is countable when referring to an individual treatment session ('a dialysis') but is more commonly used as an uncountable noun referring to the procedure or therapy in general. The plural 'dialyses' exists but is rare outside technical writing.
Easily confused with dialysis
Paralysis is loss of muscle function, while dialysis is a treatment that filters the blood when the kidneys fail.