Carbon-arc lamps, also known as arc lamps or carbon lamps, were popular in the early 20th century for their bright and intense light output, making them a popular choice for street lighting, film projectors, and theatrical lighting fixtures. Today, with the advent of more modern lighting technology, carbon-arc lamps have largely fallen out of use. However, for those interested in historical lighting or period reenactments, there are some synonyms to consider. These include "carbon filament lamps," "arc discharge lamps," and "carbon-vapor lamps." While not exact synonyms, they all refer to lighting technologies that are similar to carbon-arc lamps in some way.