Main entry: undefinable, indefinable
Definition: not capable of being precisely or readily described; not easily put into words
Usage: an indefinable feeling of terror; an abstract concept that seems indefinable
Main entry: unspeakable, untellable, unutterable, indefinable, indescribable, ineffable
Definition: defying expression or description
Usage: indefinable yearnings; indescribable beauty; ineffable ecstasy; inexpressible anguish; unspeakable happiness; unutterable contempt; a thing of untellable splendor