NOUN (2)

1. a member of one of four linguistic divisions of the prehistoric Greeks;

2. the ancient Greek inhabitants of Attica and related regions in Ionia;


ADJECTIVE (1)

1. of or pertaining to the ancient Ionians who lived in Attica and related territories, to their Ionic dialect of Greek, or to their culture;

The Collaborative International Dictionary of English v.0.48:

Ionian \I*o"ni*an\, a. [L. Ionius. See Ionic.]
   Of or pertaining to Ionia or the Ionians; Ionic. -- n. A
   native or citizen of Ionia.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Ionian
    adj 1: of or pertaining to the ancient Ionians who lived in
           Attica and related territories, to their Ionic dialect of
           Greek, or to their culture
    n 1: a member of one of four linguistic divisions of the
         prehistoric Greeks
    2: the ancient Greek inhabitants of Attica and related regions
       in Ionia