(adjective) : Īōnĭus, a, um, , = Ἰώνιος or Ἰόννιος
* Of or belonging to Ionia, Ionian: attagen,Plin. 10, 48, 68, § 133: Ionium mare (or poet. aequor), or Ionii fluctus, Ionius sinus; or subst.: Ionium, i, n., the Ionic Sea, in the west of Greece: mare,Mel. 1, 3, 3; Plin. 3, 8, 14, § 88; Liv. 23, 33, 22; Verg. A. 5, 193: aequor,Ov. M. 15, 700: fluctus,Verg. G. 2, 108: sinus,Hor. Epod. 10, 19; and simply Ionium: insulae Ionio in magno,Verg. A. 3, 211: per Ionium vectus,Prop. 3 (4), 21, 19.(but Ionia is a false reading for Jovis, Plin. 37, 7, 29, § 103).
* Subst.: Iōnĭa, ae, f., = Ἰωνία,Ionia, a country of Asia Minor on the Aegean Sea, between Caria and Aeolis, Mel. 1, 17; 2, 7, 4; Plin. 5, 29, 31, § 112; Nep. Alc. 5, 6; Prop. 1, 6, 31; Ov. F. 6, 175 al.

Male Personal name
Confirmed occurences in the Roman Empire:

• Q. Axius Aelianus Ionius (Masc, eques), ref: PIR A 1688 | PIR ID2808
• Q. Axius Aelianus Iunior Ionius (Masc), ref: PIR A 1689 | PIR ID2809
• Ionius (Masc), ref: PIR I 0041 | PIR ID7099