indefinable

adjectives

not capable of being precisely or readily described; not easily put into words

"an indefinable feeling of terror"; "an abstract concept that seems indefinable"

defying expression or description

"indefinable yearnings"; "indescribable beauty"; "ineffable ecstasy"; "inexpressible anguish"; "unspeakable happiness"; "unutterable contempt"; "a thing of untellable splendor"

indefinable, indescribable, ineffable, unspeakable, untellable, unutterable