nidan verb with 'u' ending (archaic), intransitive verb
to be possible; to be conceivable; to be likely
Archaic Nidan verb form of modern あり得る (ありえる). Used in classical Japanese to express possibility or likelihood. Not used in modern speech; learners will encounter it only in historical texts.
See also: あり得る
古典では「有り得」と書いて「ありう」と読むことがある。
In classical texts, 有り得 is sometimes read as ありう.
「ありうべきこと」という表現が古
The expression ありうべきこと (something that could be) is found in old writings.
Archaic Nidan verb form of 有り (あり, 'to be') + 得 (う, 'to get, to be possible'). The modern form あり得る (ありえる) developed from this classical conjugation.