The Collaborative International Dictionary of English v.0.48:

Milesian \Mi*le"sian\, a. [L. Milesius, Gr. ?.]
   [1913 Webster]
   1. (Anc. Geog.) Of or pertaining to Miletus, a city of Asia
      Minor, or to its inhabitants.
      [1913 Webster]

   2. (Irish Legendary Hist.) Descended from King Milesius of
      Spain, whose two sons are said to have conquered Ireland
      about 1300 b. c.; or pertaining to the descendants of King
      Milesius; hence, Irish.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Milesian \Mi*le"sian\, n.
   1. A native or inhabitant of Miletus.
      [1913 Webster]

   2. A native or inhabitant of Ireland.
      [1913 Webster]