sign

Compared meaning: a visible mark that shows meaning (noun).

比较义项：表示某种意思的记号、标志（名词）。

• sign 本词

  Refers to a deliberate gesture or symbol meant to convey a message, often understood by convention (e.g. a hand sign, a warning sign); implies communicative intent.

  指为了传达某种信息而做出的手势或符号，通常约定俗成（例如手势、警示牌）；暗示有交流意图。

  He made a sign for us to be quiet during the meeting.

  他做了个手势示意我们在会议期间保持安静。

• mark

  Refers to a visible trace, spot, or symbol left on a surface, often unintentional or physical, and does not necessarily communicate anything.

  指留在表面上的可见痕迹、斑点或符号，往往是无意造成的、具有物理性质，不一定传达任何信息。

  The old table has a dark mark where someone spilled coffee.

  那张旧桌子上有一块深色的痕迹，是有人洒了咖啡留下的。

Both can mean a visible symbol. Sign is a symbol meant to send a message, understood by convention; 'a sign of trouble' is not compared. Mark is a visible trace left on a surface, often unintentional; 'a good mark on a test' is not compared.

两者都指能传达信息的可见标记，但 sign 常指有意做出的、约定俗成的示意动作或标志，而 mark 更常指留在物体表面的痕迹或做的记号，不一定带有交流意图。这里不比较 mark 的“分数，标准”等其他义项，也不比较 sign 的“迹象，征兆”等其他义项。

Compared meaning: to make a gesture to communicate (verb).

比较义项：打手势示意（动词）。

• signal

  Signal means to give a sign using any means, such as a hand wave, a flashing light, or a sound, usually to convey one clear instruction like stop, turn, or wait; it need not involve the hands.

  signal 表示通过任何方式发出信号，比如挥手、闪灯或声音，通常用来传达停止、转弯或等待等某个明确的指令；不一定要用手。

  The lighthouse signaled the ship with a flashing light.

  灯塔用闪烁的灯光向那艘船发出信号。

• sign 本词

  Sign means to use hand gestures, close to sign language, to communicate a specific message, especially when speech is impossible or when talking to a deaf person.

  sign 表示用手势（类似手语）来传达某个具体的信息，尤其用于无法说话或与聋人交流的场合。

  The deaf man signed his order to the coffee shop worker.

  那位聋人向咖啡店店员打手势，示意自己点的东西。

Both can mean to communicate with a gesture. Signal means giving a sign using any method, like waving or a light. Sign means using hand gestures, like sign language, when speech is impossible or with a deaf person; signing your name is not compared.

这两个词都表示“用动作或信号示意”，容易混淆：signal 语义更宽泛，可以通过挥手、闪灯、声音等任何方式发出信号，常用来传达停止、转弯等具体指令；sign 则专指用手势（类似手语）来示意，尤其用于无法说话或与聋人交流的场合。这里不比较 sign 表示“签名”或作名词表示“标志”的用法，也不比较 signal 作为名词“信号”或表示“预示”的其他动词用法。