expression
irresistible; compelling; unable to help oneself
Describes a strong inner urge or unavoidable circumstance that forces one to act, often despite one's will. Frequently used in the pattern 〜やむにやまれぬ思い or 〜やむにやまれぬ事情. The expression is somewhat literary and formal.
やむにやまれぬ事情で、彼は会社を辞めた。
Due to unavoidable circumstances, he quit his job.
やむにやまれぬ思いから、彼女はその計画に反対した。
Out of an irresistible feeling, she opposed the plan.
The continuative form (連用形) of the same expression, used adverbially to mean 'unavoidably' or 'compelled by circumstances'. やむにやまれぬ is the attributive form (連体形) and modifies nouns.
Means 'unavoidable' or 'have no choice', but is more about external circumstances rather than an inner compulsion. やむにやまれぬ emphasizes an irresistible internal drive.
From the verb 止む (to stop) in the negative continuative form 止まず (not stopping), reduplicated with the particle に, and the negative auxiliary ぬ (classical equivalent of ない). Literally 'not stopping, not stopping', i.e., an unstoppable feeling or situation.