accidental

Compared meaning: not done on purpose (adjective).

比较义项：非故意的、无意间造成的（形容词）。

• accidental 本词

  Broadest word for something happening by chance, without plan or intention; can describe events, outcomes or actions, and is common in everyday spoken English.

  范围最广的词，指事情纯属偶然发生，没有计划或意图；可以形容事件、结果或行为，在日常口语中很常见。

  Their meeting at the airport was completely accidental, not planned at all.

  他们在机场的相遇完全是偶然的，事先毫无计划。

• unintentional

  Neutral, direct opposite of 'intentional'; focuses on the doer's lack of purpose behind an action or its effect, often used when explaining or apologizing.

  语气中性，是“故意的”的直接反义词；侧重说明行为者做某事或造成某种效果时并非出于本意，常用于解释或道歉的场合。

  The insult was unintentional, but she still felt hurt by it.

  那句冒犯的话并非故意的，但她还是因此感到受伤。

• unwitting

  Stresses that the person had no awareness or knowledge of what was happening at the time; usually describes a person drawn into something without realizing it.

  强调当事人当时并不知情、没有意识到正在发生的事情；通常用来形容某人在不知不觉中被卷入某件事。

  The tourists became unwitting accomplices in the scam without realizing it.

  那些游客在不知不觉中成了骗局的同谋，自己却浑然不觉。

• inadvertent

  More formal and written in tone; typically describes small mistakes or slips caused by carelessness or inattention, not by chance or lack of awareness.

  语气更书面、正式，通常形容因疏忽或不留神而造成的小失误，而不是纯粹的偶然或不知情。

  The typo was an inadvertent slip caused by typing too fast.

  那个错别字是因为打字太快而造成的无心失误。

All four mean 'not done on purpose'. Accidental stresses pure chance, with no plan. Unintentional is neutral, focusing on the doer not meaning the result. Unwitting stresses no awareness at the time, usually for people. Inadvertent is more formal, for a small mistake from carelessness.

这四个词都表示“并非故意”，但侧重点不同：accidental 强调纯属偶然、事先没有计划；unintentional 语气中性，强调行为者本意并非如此；unwitting 强调当事人当时并不知情，多用于形容人；inadvertent 语气较正式，强调因疏忽大意而造成的小差错。