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• red light
  red light

  noun

  a red lamp, used as a traffic signal to mean “stop.”
• red-light
  red-light

  verb (used with object)

  to stop or deter by means of or as if with a red light.

red light

¹ American  

noun

1. a red lamp, used as a traffic signal to mean “stop.”

2. an order or directive to halt an action, project, etc..

   There's a red light on all unnecessary expenses.

3. a children's running game in which players must stop when “Red light!” is called.

4. a signal of danger; warning.

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red-light ² American  

[red-lahyt] / ˈrɛdˈlaɪt /

verb (used with object)

red-lighted, red-lighting

1. Informal. to stop or deter by means of or as if with a red light.

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red light British  

noun

1. a signal to stop, esp a red traffic signal in a system of traffic lights

2. a danger signal

3. an instruction to stop or discontinue

4. 1. a red lamp in a window of or outside a house indicating that it is a brothel

   2. ( as modifier )

      a red-light district

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Etymology

Origin of red light¹

First recorded in 1840–50

Origin of red-light²

First recorded in 1895–1900

Example Sentences

On the same floor, a neon bed is bathed in red light.

From Los Angeles Times • May 20, 2026

This year, attendees can sign up for free massages, red light therapy sessions, lymphatic drainage boots, and—thanks in part to a partnership with LEGO—partake in a series of analog “adult play” installations.

From Slate • May 8, 2026

The new offering will likely include an infrared sauna and a red light therapy bed, among other things.

From Los Angeles Times • May 5, 2026

While there are encouraging signs that red light therapy may help in some different areas - from skin rejuvenation to muscle soreness - Dr Sophie Weatherhead, from the British Association of Dermatologists, is also cautious.

From BBC • May 2, 2026

Even with the thickened summer fog, even though Cat couldn’t see it, she knew the little red light glowed on.

From "Caterpillar Summer" by Gillian McDunn

Related Words

• traffic signal