Source : Webster's Revised Unabridged Dictionary (1913)

Unearthly \Un*earth"ly\, a.
   Not terrestrial; supernatural; preternatural; hence, weird;
   appalling; terrific; as, an unearthly sight or sound. --
   {Un*earth"li*ness}, n.

Source : WordNet®

unearthly
     adj 1: concerned with or affecting the spirit or soul; "a spiritual
            approach to life"; "spiritual fulfillment"; "spiritual
            values"; "unearthly love" [syn: {spiritual}]
     2: suggesting the operation of supernatural influences; "an
        eldritch screech"; "the three weird sisters";
        "stumps...had uncanny shapes as of monstrous creatures"-
        John Galsworthy; "an unearthly light"; "he could hear the
        unearthly scream of some curlew piercing the din"- Henry
        Kingsley [syn: {eldritch}, {weird}, {uncanny}]