Ion, in physics and chemistry, an atom or group of atoms with a net electric charge

Ionic bond, a type of chemical bond involving ions

Ionian Islands, seven Greek islands which lie on the eastern coast of the Ionian Sea

Ionia, an ancient region in western Anatolia, in which the Ionian settlers established some colonies.

Ionic liquid, a liquid that essentially contains only ions

Ionian Revolt, a revolt by Greek Ionians against the Persian Empire

Ionic radius, a measure of the size of an ion in a crystal lattice

Ionic order, one of the orders of classical architecture

Ionic strength, a function of the concentration of all ions present in a solution

Ionian School, in ancient Greek philosophy

Ionic numeral system, a certain numeral system with Greek numerals

Ionic Greek, any of several related dialects in the ancient Greek language

Ionic compound, a chemical compound in which ions are held together in a lattice structure by ionic bonds

Ionic solid, a solid are held together by ionic bonds

Ionians, a people, one of the four great divisions of the ancient Greek people

Ionian Sea, an arm of the Mediterranean Sea between Greece and Southern Italy

Ionian Technologies, a biotechnology company

Ionian mode, one of the modes in ancient Greek music

The Middle Pleistocene, also known as the Ionian Stage, in geology

SS Ionic, a steamship ocean liner built for the White Star Line (1902)

Ionic equation, a chemical equation in which electrolytes are written as dissociated ions

Ionic transfer, the transfer of ions from one liquid phase to another

Ionic crystal, a crystal consisting of ions bound together by their electrostatic attraction

Ionic polarization, polarization caused by relative displacements between ions in ionic crystals

Ionic potential, the ratio of electric charge to the radius of an ion