Ionian UK /aɪˈəʊni.ən/US /aɪˈoʊni.ən/adjective 6noun 3forms 1 adjective6 •Relating to the Hellenic people of that name. •Pertaining to Ionia, the ancient (ca 1100 BC) region including western Asia Minor and the adjacent Aegean Islands occupied by the Ionian people. •Designating the Ionian mode or scale; the name of the major key in modal theory. •Synonym of Ionic. •Relating to Io, one of the moons of the planet Jupiter.Bagenal, Dowling & McKinnon (2007), Jupiter: The Planet, Satellites and Magnetosphere. Cambridge University Press, p. 313. Despite the variations in Ionian vulcanism ... •Relating to the asteroid (52) Io. noun3 •A member of the Ionians, one of the races of Ancient Greece. •Ellipsis of Ionian Sea: A sea in the central and east central part of the Mediterranean. •An inhabitant of Io, a moon of Jupiter. formsIonians