Producing no result, even though real effort was made. This word almost always describes an effort, and it carries the sadness of that effort being wasted: unavailing attempts, unavailing efforts, an unavailing struggle. The classic pattern is a rescue or a plea — 'their attempts to revive him were unavailing' — and you will meet it mostly in news reports, novels, and formal writing. It is genuinely old-fashioned and literary; a Taiwanese student can read it happily but has almost no reason to say it, and using it in conversation would sound like you had swallowed a nineteenth-century novel. What makes it different from 'useless' is dignity. 'Useless' judges the thing and often blames someone. 'Unavailing' just reports that the effort, sincere and hard, did not change the outcome — it is the kinder word, and it is nearly always used about people who tried their best.

徒勞無功的、無濟於事的