the.com/ion engine

means A spacecraft propulsion system that ionizes a gas and uses electric fields to accelerate the charged particles out a nozzle, producing tiny amounts of thrust extremely efficiently over long periods.

from The 'ion' half comes from Greek 'ienai,' meaning 'to go' — the same root that gives us 'ion' in chemistry, coined in the 1830s for particles that migrate toward electrodes. 'Engine' traces back through Old French 'engin' to Latin 'ingenium,' meaning natural talent or cleverness — the same root behind 'ingenious.' The technology itself was first seriously proposed and tested in the mid-20th century, with real spaceflight use beginning in the latter part of that century, built on the simple idea that electrically charged atoms, flung out fast enough, can push a craft forward even with almost no fuel mass.