placid

Compared meaning: peaceful, not disturbed or upset (adjective).

比较义项：平静的（形容词）。

• quiet

  Describes the absence of noise or disturbance in a place or moment; the most common, neutral word, often used for physical silence rather than an emotional state.

  形容某个地方或某一时刻没有噪音或干扰；是最常见、语气中性的词，多指物理上的安静，而非情绪状态。

  The library was quiet except for the sound of turning pages.

  图书馆里很安静，只有翻书的声音。

• calm

  Focuses on an emotional or mental state free from anxiety, nervousness or agitation; used for people's feelings or a tense situation, not physical silence.

  侧重情绪或心理状态，没有焦虑、紧张或激动；多用于描述人的心情或紧张的局势，而非物理上的安静。

  Take a deep breath and try to stay calm during the exam.

  深呼吸，努力在考试中保持镇定。

• placid 本词

  Describes a smooth, undisturbed calmness, often in a literary tone; typically used for water, scenery, or an unruffled personality, sometimes sounding distant.

  形容一种平滑、不受扰动的平静，语气偏书面；常用于描写水面、景色，或形容性情沉稳不易激动的人，有时略带疏离感。

  The lake was placid, without a single ripple on its surface.

  湖面平静无波，没有一丝涟漪。

Quiet, calm, and placid can all mean peaceful. Quiet stresses the absence of noise in a place. Calm stresses freedom from anxiety, in a mind or situation. Placid describes undisturbed stillness, often literary, used for water, scenes, or temperament. Not compared: quiet meaning not talkative.

这三个词都可表示“平静的”，但侧重不同：quiet 强调没有噪音或喧闹，多指环境的安静；calm 强调没有焦虑或紧张情绪，多用于人的心情或紧张的局势；placid 强调平静无波动，常用于水面、场景或性情，语域偏书面。这里不比较 quiet 表示“不爱说话的”等其他义项。