impulse

Compared meaning: a sudden wish to do something, without thinking (noun).

比较义项：未经理性思考、突然产生的想做某事的念头（名词）。

• impulse 本词

  Suggests a strong, often hard-to-resist urge to act suddenly; used in the fixed phrase 'on impulse' (no article) and can describe fairly serious or emotional actions.

  指强烈、往往难以抗拒的、想要突然行动的冲动；常用于固定短语“on impulse”（不加冠词），可用来描述较严重或情绪化的行为。

  She bought the shoes on impulse without really thinking about it.

  她一时冲动买下了那双鞋，并没有认真考虑。

• whim

  Suggests a lighter, more frivolous or playful sudden idea, often trivial and not based on any real reason; used with an article, as in 'a whim' or 'on a whim'.

  指较轻松、随性甚至没有明确理由的一时念头，通常显得轻率或不太认真；常带冠词，构成“a whim”或“on a whim”。

  On a whim, they decided to drive to the beach.

  他们一时兴起，决定开车去海滩。

Impulse and whim both mean a sudden idea to do something. Impulse is stronger, suggesting a hard-to-resist urge, used in the phrase on impulse, without an article. Whim is lighter and more playful, often trivial, used with an article, as in a whim.

这两个词都表示“一时的念头或冲动”，语境相近，但impulse更强调强烈、难以控制的冲动，语气较重；whim则更随性，带有一点任性或不太认真的意味，语气较轻。此外，whim常带冠词构成“on a whim”，impulse则用不带冠词的“on impulse”。

Compared meaning: a brief burst of energy or signal (noun).

比较义项：脉冲，短暂出现的能量或电信号（名词）。

• pulse

  Pulse is the broader term for any brief burst of energy, sound, or electrical current, often one in a repeating series, such as radar or laser pulses.

  pulse 是更宽泛的说法，指任何短暂出现的能量、声音或电流爆发，往往是重复出现的一系列信号中的一个，例如雷达脉冲或激光脉冲。

  The radar sends out a pulse every few seconds to detect nearby aircraft.

  雷达每隔几秒发出一次脉冲信号，用来探测附近的飞机。

• impulse 本词

  Impulse specifically denotes a brief electrical or nerve signal that triggers a response, common in physiology and electronics, and is usually a single, non-repeating event.

  impulse 特指触发某种反应的短暂电信号或神经信号，常用于生理学和电子学领域，通常是单次、不重复出现的事件。

  An electrical impulse travels along the nerve to make the muscle contract.

  一个电脉冲沿着神经传导，使肌肉收缩。

Pulse and impulse both mean a brief burst of energy, but differ. Pulse is broader, often repeating, like radar or laser pulses. Impulse means a brief electrical or nerve signal that triggers a response. Not compared: pulse's 'heartbeat' meaning, and impulse's 'sudden urge' meaning.

这两个词在“脉冲”这一义项上意思相近，都指短暂出现的信号或能量爆发，但 pulse 更常指周期性、可重复出现的脉冲（如脉搏、雷达波），语域更中性；impulse 更强调触发某种反应的单次电信号或神经信号，常见于科学和技术语境。这里不比较 pulse 的“脉搏、心跳”义，也不比较 impulse 的“一时冲动”义。