In logic, some statements can't be proven true, only proven false.
For example, the statement "the universe is infinite" can be disproven by discovering its bounds, say by launching a rocket that crashes into the all-encompassing, mysterious wall near a galaxy far, far away; but cannot be proven true, as the case of an infinite universe is observationally indistinguishable from the case of a universe "so large we haven't found its bounds yet".
The term I'm looking for could be viewed as equal and opposite to "unfalsifiable", in that I'm looking for a term roughly equivalent to "untruthable". Does such a term exist? Also, does the term "unfalsifiable" hold this strict interpretation of "provably true or unknowable" in logic, as I've only ever heard it used in the context of philosophy?