ENGLISH
REFERENCE

ion

n. countable
C1 Advanced US //ˈaɪˌɑn// UK //ˈaɪɒn// ion Slang

n. a tiny particle that has an electrical charge because it has gained or lost electrons.

n. an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.


SIMPLE

Salt dissolves in water to form sodium and chloride ions.

CONTEXTUAL

The battery works by moving lithium ions between the positive and negative electrodes during the charging cycle.

COMPLEX

In the upper atmosphere, solar radiation strips electrons from gas molecules, creating a layer of ions that can reflect radio waves back to Earth.

Etymology 1

From the ending of anion and cation, which in turn is from Ancient Greek ἰόν (ión, “going”), neuter present participle of εἶμι (eîmi, “I go”). Coined by English polymath William Whewell in 1834 for Michael Faraday, who introduced it later that year.

Etymology 2

From a reduction of I don't.

Usage

Commonly used in chemistry and physics; often modified by 'positive', 'negative', 'metal', or 'hydrogen'.

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