When the probability describes the likelihood of our data matching a particular theory, there is only "seems improbable". E.g. it seems improbable that there a

When the probability describes the likelihood of our data matching a particular theory, there is only "seems improbable". E.g. it seems improbable that there are other yet undetected Pluto-sized objects in the solar system. Is it improbable? No, it's either true that there are such objects or not. As opposed to events that have not occurred. E.g. it seems improbable that ten flips of a fair coin will yield ten heads. Is it improbable? Yes by most definitions of improbable, it is improbable.