What does dialyser mean?
A dialyser is a device that carries out dialysis — the separation of substances in a liquid by passing them through a semipermeable membrane. Its most familiar role is medical: in haemodialysis, a dialyser acts as an artificial kidney, drawing waste products such as urea and excess water out of the bloodstream of patients whose kidneys can no longer do the job. Inside a typical unit, blood flows along thousands of hair-thin hollow fibres made of a membrane material, while a cleansing fluid called dialysate flows on the other side; small waste molecules cross the membrane while blood cells and proteins stay behind. The term also covers laboratory and industrial apparatus used to purify solutions, such as removing salts from protein samples. The spelling "dialyser" is standard in British English, with American English preferring "dialyzer". Though largely clinical in register, the word has become quietly familiar to the many families affected by kidney disease worldwide.
nounA dialyser is a device used in dialysis, especially the artificial kidney machine that filters waste products from the blood of patients with kidney failure. It may also refer more generally to any apparatus that separates substances by means of a semipermeable membrane.
- A medical apparatus, particularly in haemodialysis, that removes waste products and excess fluid from the blood of patients with impaired kidney function.
- Any laboratory or industrial device that effects dialysis — the separation of particles in a liquid using a semipermeable membrane.
"The patient travels to the clinic three times a week for treatment on a dialyser."
"Modern dialysers use thousands of hollow fibres to maximise the surface area available for filtering the blood."
"In the biochemistry lab, the researchers placed the protein solution in a dialyser overnight to remove excess salt."
The regular plural applies when referring to multiple devices, whether in a hospital ward or a manufacturing context.
"The ward keeps a stock of spare dialysers in case a unit fails mid-treatment."
Every year, millions of people owe their lives to a device whose name comes from the Greek word for 'to loosen apart' — the dialyser literally unbinds waste from blood.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dialyser
The word dialyser derives from "dialysis", which comes from the Greek "dialyein" (διαλύειν), meaning "to dissolve" or "to loosen apart", formed from "dia-" (apart) and "lyein" (to loosen). The scientific sense of separating substances across a membrane was established in chemistry during the nineteenth century, notably in the work of Thomas Graham on diffusion, and the agent noun was formed with the suffix "-er" to denote the apparatus performing this action. It shares its Greek root with words such as "analysis" and "paralysis".
Related word forms
How dialyser is actually used
The spelling "dialyzer" with -z- is standard in American English, while British English typically uses "dialyser" with -s-. The word is technical and clinical in register, appearing mainly in medicine, nursing, and laboratory contexts rather than everyday conversation. In casual speech people are far more likely to say "kidney machine" or "dialysis machine" than "dialyser".
Easily confused with dialyser
An analyser is an instrument for examining the components of something, whereas a dialyser specifically separates substances through a semipermeable membrane as in kidney dialysis.