What does deioniser mean?
A deioniser is an apparatus or treatment system that removes dissolved ions from water or another liquid. The ions it targets are electrically charged particles, including the calcium and magnesium ions associated with hard water. Removing them produces deionised water, which is widely used in laboratories, boilers, manufacturing processes, electronics, and household appliances such as irons. A deioniser is not the same as a general filter: filtration may remove suspended particles, while deionisation specifically addresses dissolved ions. Nor does it necessarily remove every possible contaminant, so deionised water should not automatically be treated as drinking water. The term is especially associated with British spelling, although the concept and equipment are used internationally; American English more commonly spells the device deionizer and the resulting water deionized.
nounA device or system for removing dissolved ions from a substance, especially water. The process is commonly used to produce deionised water for laboratory, industrial, or domestic purposes.
- An apparatus or system that removes dissolved ions, especially from water, producing deionised water.
"The laboratory uses a deioniser to prepare high-purity water for its experiments."
"The factory installed a new deioniser to supply the production line with deionised water."
"Before using the glassware, the technician passed the solvent through a laboratory deioniser."
The standard plural adds -s to the noun; in American spelling, the corresponding plural is deionizers.
"Several deionisers are installed throughout the building."
A deioniser has a precise job: it removes dissolved ions without necessarily eliminating every other contaminant, so purified water is not automatically safe to drink.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does deioniser come from?
Deioniser is an English formation built from de-, meaning removal or reversal, and ion, together with the combining form -ise and the agent suffix -er. The scientific word ion comes from Greek iōn, meaning “going,” a usage developed in the study of electricity and charged particles. Related English words include ionise, ionic, ionisation, and ionosphere.
Related word forms
How deioniser is actually used
The form with -iser is standard in British English, while deionizer is the usual American spelling. The word is chiefly technical and appears in water treatment, laboratory, industrial, and maintenance contexts.
Easily confused with deioniser
A deioniser specifically removes dissolved ions, whereas a demineraliser more broadly removes mineral salts and may use processes such as ion exchange, reverse osmosis, or distillation.