if necessary; when unavoidable
Formal, set phrase meaning 'if it cannot be helped' or 'if there is no other choice'. Used to introduce a reluctant action or condition.
If it's unavoidable, we are considering postponing the meeting.
If necessary, I will handle the negotiations directly.
やむを得ない is the more common, shorter form meaning 'unavoidable' or 'cannot be helped'. ばんやむをえなければ is a formal, emphatic conditional version with 万 (ばん) adding a sense of 'by all means' or 'if absolutely necessary'.
Kanji spelling using 止む; very rare and literary. The phrase is almost always written in kana.
Kanji spelling using 已む; very rare and literary. The phrase is almost always written in kana.
Derived from やむを得ない (unavoidable) with the prefix 万 (ばん) meaning 'ten thousand' or 'all', intensifying the sense of absolute necessity, and the conditional ば form.