stoplight

stoplight — noun

1. a roadside signal at a junction that shows three colors — red for stop, yellow f

1.nounA2
Definition

a roadside signal at a junction that shows three colors — red for stop, yellow for caution, and green for go — telling drivers when they must stop and when they may move forward.

Example

Ravindra slowed down when he saw the stoplight ahead change from green to yellow.

demonstrates color transition sequence

A red stoplight means you must come to a complete stop before the white line.

red + stoplight for the stop instruction

Common collocations
  • wait at a stoplight
  • run a stoplight
  • stoplight turns red / green / yellow
  • go through a stoplight
  • stoplight changes
Synonyms
  • traffic light

    the more common international term, used in both US and UK English

  • traffic signal

    the formal or official term, often used by transportation authorities

  • signal light

    less common; used mainly in technical or engineering contexts

Grammar Patterns

the + stoplight + verb (changes / turns / shows)

at a / the stoplight

Usage Note

Stoplight for a traffic signal is the standard term in American English. In British English, the equivalent word is traffic light.

Common Mistakes

I ran a red stoplight because I was in a hurry.
I went through a red light because I was in a hurry.
'Ran a red light' is a fixed expression; do not insert 'stop' into it.
The stoplight was broken so all directions stayed red.
The traffic signal was broken so all directions showed red.
In formal or official contexts, traffic signal or traffic light is preferred.

2. a red lamp on the back of a vehicle that turns on when the driver uses the brake

2.nounB1
Definition

a red lamp on the back of a vehicle that turns on when the driver uses the brakes, to warn other road users that it is slowing or stopping.

Example

Quinn noticed that the left stoplight on his car was not working after the crash.

possessive + left stoplight indicating location

When Hamza braked suddenly, the red stoplights on the back of his truck lit up.

stoplights + verb phrase lit up

Common collocations
  • rear stoplight
  • stoplight comes on / lights up
  • broken / burned-out stoplight
  • left / right stoplight
Synonyms
  • brake light

    the standard international term, more common in technical and UK English contexts

  • brake lamp

    formal term, used in repair manuals and vehicle specifications

Grammar Patterns

possessive + stoplight + verb (comes on / lights up / is broken)

a / the + stoplight + on / at the rear of + vehicle

Usage Note

In this sense, stoplight is primarily an American term. The more common and internationally understood word is brake light. Tail light is different — it stays on whenever the headlights are on and does not signal braking.

Common Mistakes

The stoplight on my car stays on all night.
The tail light on my car stays on all night.
A stoplight (brake light) only comes on when you press the brake pedal. The light that stays on is the tail light.
I need to replace a stoplight bulb — it stays dark even when I press the brake.
I need to replace a brake light bulb
it stays dark even when I press the brake.' — Brake light is the more precise term for the replacement part.

Synonym discussion

Sense: noun/1

All three terms refer to the red-yellow-green lights at road junctions, but they differ in region and register. Stoplight is the everyday American word — you would say 'turn left at the stoplight' in casual conversation across the US. Traffic light is the standard term used internationally and in both American and British English; it is the safest choice for learners. Traffic signal is the formal or official term used by transportation departments, in road safety laws, and in engineering manuals — for example, 'the traffic signal was out of order due to a power failure.' While stoplight feels informal and regionally specific, traffic light and traffic signal carry no regional limitation. A useful tip: if you are writing for a global audience, choose traffic light; if you are in the US and speaking casually, stoplight is fine.

stoplight ↗traffic lighttraffic signal

Common collocations

Nouns

  • stoplight turns
  • stoplight changes

Phrases

  • wait at the stoplight
  • go through the stoplight
  • run a stoplight

Prepositions

  • at a / the stoplight
  • through a / the stoplight

Etymology

English

Stoplight is a compound word formed from 'stop' (to halt) and 'light' (a source of illumination). The term entered English around the 1910s, shortly after the first red-green electric traffic signals were installed in the United States. The brake-light sense developed later in the mid-20th century as automotive rear lighting systems became standardized — the same logic of 'a light that tells you to stop' was extended from the intersection to the car.