The word "streetlight" is a common noun that refers to a light fixture that illuminates streets and other public spaces at night. There are several synonyms for this word, including lamppost, light pole, street lamp, and street fixture. Each of these synonyms can be used interchangeably with "streetlight" to describe the same object. Some other related words include "floodlight," which is a type of light that projects a bright beam of light over a wide area, and "lantern," which is a smaller, portable light source often used for camping or other outdoor activities.