an atom in which one, or more than one, electron is missing from one of its electronic shells, causing the atom to have a positive charge
an atom or a molecule that has lost an electron
an atom (or group of atoms) that has lost electrons (see The Atom below) and a negative ion is an atom (or group of atoms) that has gained electrons
an atom with one electron missing
Any atom missing one or more of its electrons. In the case of a hydrogen atom, which has only one electron, the ion is simply a proton.
An atom having a net positive charge due to the loss of one of its negatively charged electrons.
Atom that has lost one or more valence electrons resulting in a net positive charge.