"Semafórico" is an adjective derived from "semáforo," which means "traffic light" in English. "Semafórico" is often used to describe things related to traffic lights or their operation. It is used in both oral and written Spanish, but more commonly in written contexts.
Examples
El sistema semafórico de esta intersección necesita ser actualizado.
Translation: The traffic light system at this intersection needs to be updated.
Por favor, respeta la señalización semafórica y no cruces en rojo.
Translation: Please respect the traffic light signals and do not cross on red.
Idiomatic Expressions
1. "Ponerse en verde"
Meaning: To turn green (said of a traffic light).
Example: Espera un momento, el semáforo se pondrá en verde.
Translation: Wait a moment, the traffic light will turn green.
2. "Estar en ámbar"
Meaning: To be on amber/yellow (said of a traffic light).
Example: El semáforo está en ámbar, disminuye la velocidad.
Translation: The traffic light is on amber, slow down.
3. "Saltarse un semáforo en rojo"
Meaning: To run a red light.
Example: Si te saltas un semáforo en rojo, te pueden multar.
Translation: If you run a red light, you can get fined.
Etymology
The term "semáforo" comes from the Greek roots "sema" meaning "sign" and "pherein" meaning "to carry," and was coined by the naval officer and inventor Mariano Semper Roldán in 1868.