Billboards are a type of advertising medium that is used for marketing and promotional purposes. There are several other synonyms for billboards that are used interchangeably such as hoardings, outdoor advertising, and signage. Hoardings refer to large boards that are placed in public areas for promotional purposes. Outdoor advertising is a form of marketing that reaches people while they are outside of their homes or offices. Signage, on the other hand, is an umbrella term that refers to all types of signs including billboards, banners, and posters. All of these synonyms for billboards are used to capture the attention of potential customers and promote products and services in a highly visible, impactful way.