general Englishneutraltechnical
- A traffic signal indicating that vehicles must stop.
general Englishinformalformal
- A signal, decision, or sign that forbids, disallows, or terminates an action or project.
general Englishtechnicalneutral
- A warning indicator on equipment or instruments signaling attention, malfunction, or an operational condition requiring action.
general Englishinformaleuphemistic
- A reference to prostitution or sexually explicit entertainment, often by association with a 'red-light district' or similar venue.