Sodium lamps often referred to as High-Pressure Sodium or HPS lamps, are commonly used in outdoor lighting due to their efficiency and long life. However, there are several synonyms for sodium lamps such as high-intensity discharge (HID) lamps, which also include mercury vapor and metal halide lamps. Additionally, sodium lamps can also be referred to as yellow lamps, due to their characteristic yellowish-orange light. These lights are used for street lighting because they provide good visibility at night, making them ideal for urban and suburban environments. Overall, sodium lamps have multiple synonyms and are a popular choice for lighting solutions due to their efficiency and longevity.