The Oxford Thesaurus An A-Z Dictionary of Synonyms - elusive adj.

1) evasive, slippery, tricky, shifty: One of the world's most elusive guerrilla leaders was spotted in public yesterday. 2) evasive, evanescent, fleeting, fugitive, transitory, indefinable, elusory, intangible, impalpable: The notion of truth has always been elusive.