Can someone please sort out these simple chemistry definitions which, to me, seem contradictory?

Ok you are not looking closely at the words. A molecule is an electrically neutral group of atoms bonded together meaning it has no net charge (+ or -). An ion is electrically unstable because it has a charge but wants to be neutral in order to be electrically stable. An ion can either be a cation + charged species or an anion - charged species, An ion can either be a charged atom like Cl- (anion) or like Na+ (cation) or it can be a molecular ion, that is a group of atom bound together that have a net charge like - OH or something like NH4+. These last two are molecular ions because they are groups of atoms bound together but they are not neutral they carry a net charge. Strictly a molecule has no charge, a molecular ion is charged. hope that cleared it up.