hypothetical
Used to describe something that is based on a hypothesis or assumption, often in academic or logical contexts. Not a common everyday word.
That argument is based on a hypothetical premise.
We considered countermeasures assuming a hypothetical situation.
Compound of 仮言 (kagen, 'hypothesis' or 'conditional statement') + 的 (-teki, '-like'). The exact historical derivation is uncertain, but it follows a common pattern for forming adjectival nouns from Sino-Japanese nouns.