Meaning

noun (chemistry) two or more atoms bound together as a single unit and forming part of a molecule

noun an atom or group of atoms with at least one unpaired electron; in the body it is usually an oxygen molecule that has lost an electron and will stabilize itself by stealing an electron from a nearby mo

noun a person who has radical ideas or opinions

originPIE word *wréh₂ds Inherited from Middle English radical, from Latin rādīcālis (“of or pertaining to the root, having roots, radical”). Compare grassroots.

Etymology from Wiktionary, CC BY-SA 3.0