intangible
adjective uk/ɪnˈtæn.dʒə.bəl/ us/ɪnˈtæn.dʒə.bəl/
（感觉或性质）难以捉摸的，无法形容的，难以确定的
An intangible feeling or quality exists but you cannot describe it exactly or prove it.
She has that intangible quality which you might call charisma. 她具有一种难以捉摸的特质，你或许会称之为领袖气质。