unsatisfactory

Compared meaning: not good enough, below what is needed (adjective).

比较义项：不够好，达不到要求或期望（形容词）。

• unacceptable

  The strongest of the three: means something breaks a rule, standard, or moral limit and cannot be permitted or tolerated, often demanding that it stop or change. Common with behavior, risk, conduct.

  三者中语气最强：表示某事触犯了规则、标准或道德底线，不能被允许或容忍，往往暗示必须制止或改变。常与 behavior（行为）、risk（风险）、conduct（举止）搭配。

  Being rude to customers is simply unacceptable at this company.

  在这家公司，对顾客粗鲁无礼是绝对不能接受的。

• disappointing

  Milder and more subjective: describes something that fails to meet personal hopes or expectations, causing a feeling of letdown, without implying any rule was broken. Common with results, endings, performances.

  语气较温和、较主观：形容某事没有达到个人的期望或希望，让人感到失望，但并不意味着违反了任何规则。常与 results（结果）、endings（结局）、performances（表现）搭配。

  The ending of the movie was quite disappointing for everyone.

  这部电影的结局让每个人都相当失望。

• unsatisfactory 本词

  Formal and evaluative: means something falls short of a required or expected standard, typically used in assessments, grades, or work performance, weaker in moral force than unacceptable.

  语气正式、带评价色彩：表示某事没有达到应有的或规定的标准，常用于评估、评分或工作表现，其道德谴责的力度比 unacceptable 弱。

  His performance this month was unsatisfactory, so he needs to improve.

  他这个月的表现不合格，所以他需要改进。

Unacceptable, disappointing, and unsatisfactory all describe something not good enough. Unacceptable is strongest, meaning something breaks a rule or limit and cannot be tolerated. Unsatisfactory is formal, meaning something fails to meet a required standard. Disappointing means something does not match someone's hopes.

这三个词都可以形容“不够好”，但语气强弱和侧重点不同：unacceptable 语气最强，强调触犯规则或底线、不能容忍；unsatisfactory 语气正式，强调没有达到应有的标准；disappointing 语气较委婉、较主观，强调与期望不符、令人失望，不一定涉及规则或标准。