What does ionise mean?
To ionise is to give atoms or molecules an electrical charge by adding or removing electrons, producing particles called ions. The process can be induced by strong electric fields, radiation, heat, or chemical reactions, and is central to electrochemistry, plasma physics, mass spectrometry, and some medical treatments. The verb can be transitive, as in "ionise the air", or intransitive, as in "the gas ionises under extreme heat". It is not a general synonym for charging an object: ionisation specifically creates or results in charged atomic or molecular particles. British English uses the form "ionise", while US English normally uses "ionize". The related noun "ionisation" names the process, and the adjective "ionised" describes a substance whose particles have become ions.
verbTo convert an atom, molecule, or gas into ions, typically by adding or removing electrons and thereby giving the particles a net electrical charge. It may also occur naturally or be used intransitively to describe this process.
- To convert a substance or its constituent atoms or molecules into ions.
- To undergo conversion into ions; to become electrically ionised.
"The intense radiation in the chamber can ionise the surrounding air and create a visible flash."
"The device uses a high-voltage discharge to ionise the gas inside the chamber."
"At sufficiently high temperatures, the surrounding material will ionise and conduct electricity."
Lightning can ionise the air so violently that the sky briefly becomes a glowing web of electrically charged particles.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ionise come from?
The word is formed from "ion" and the verbal suffix "-ise", with the US spelling using "-ize". "Ion" comes through Latin from the Greek "ion", meaning "going", ultimately associated with the Greek verb "ienai", "to go". The suffix "-ise" also has Greek ancestry and was widely used in English to form verbs meaning to bring into a particular condition or action.
Related word forms
How ionise is actually used
The British spelling is normally written "ionise" and the US spelling "ionize". In technical writing, the verb is commonly used transitively with a substance as its object, as in "ionise the gas", while "the gas ionises" describes the same process intransitively. The term is primarily used in chemistry, physics, medicine, and atmospheric science.