Understand the concept of ions: Ions are atoms or molecules that have gained or lost one or more electrons, resulting in a net charge.
Differentiate between cations and anions: Cations are positively charged ions, which means they have lost electrons. Anions are negatively charged ions, which means they have gained electrons.
Identify the charge of the ion in question: The problem asks for a negatively charged ion.
Recall the definition of an anion: An anion is an ion with a negative charge, formed when an atom gains electrons.
Conclude that the correct term for a negatively charged ion is 'Anion'.