(organic chemistry) The iodonium ion (C₆H₅)₂I⁺

(astronomy, historical) A scientific instrument used to determine the orbital periods of Jupiter's moons and to compute the times of their eclipses.

To act as a caster

(transport) A form of rapid transit using buses, which have dedicated rights-of-way or laneways, purpose-built bus stations, and dedicated traffic signalling.