Grammatical term referring to the subjunctive mood, used to express hypothetical, wished, or contrary-to-fact situations. In Japanese, this often corresponds to conditional forms like 〜ば, 〜たら, or 〜なら.
The English subjunctive mood does not completely correspond to Japanese conditional expressions.
仮定法過去完了は、過去の事実に反する仮定を表す。
The past perfect subjunctive expresses a hypothesis contrary to past facts.
Compound of 仮定 (assumption, hypothesis) and 法 (law, rule, method), literally 'method of supposition'. A calque from Western grammatical terminology.