Something that is unsuccessful does not achieve what it was intended to achieve.
例句
His efforts were unsuccessful.他的努力失敗了。...a second unsuccessful operation on his knee...他第二次失敗的膝蓋手術
ADJ-GRADED
（尤指事業上）失敗的，不成功的
Someone who is unsuccessful does not achieve what they intended to achieve, especially in their career.
例句
The difference between successful and unsuccessful people is that successful people put into practice the things they learn...成功者與失敗者的區別在于成功者能夠學以致用。He and his friend Boris were unsuccessful in getting a job.他和他朋友鮑里斯都沒有找到工作。
英漢詞典釋義
adj.
不成功的；失敗的
He made an unsuccessful attempt to stop the thief.他試圖捉住小偷, 但未能成功。She was equally unsuccessful.她同樣沒有成功。
英英詞典釋義
Adjective
1. not successful; having failed or having an unfavorable outcome
2. failing to accomplish an intended result;
"an abortive revolt""a stillborn plot to assassinate the President"