ion (n.)

"positively charged ion," 1834, from Latinized form of Greek kation "going down," neuter present participle of katienai "to go down," from kata "down" (see cata-) + ienai "to go" (from PIE root *ei- "to go"). Proposed by the Rev. William Whewell, English polymath, and published by English physicist Michael Faraday. Compare ion.

coined 1891 by Irish physicist George J. Stoney (1826-1911) from electric + -on, as in ion (q.v.). Electron microscope (1932) translates German Elektronenmikroskop.