A "billboard sign" refers to a large sign, usually located near roads or highways, that displays advertisements or messages for people to see. Full definition
Along with the elation that two precious babies were growing inside of me, thoughts flashed before my mind's eye in succession like a series of billboard signs on an interstate. (twiniversity.com)
The word is on reader boards in the front lawn, and as people drive to work, they see billboard signs with pictures of a building and an invitation to «Come to Church.» (redeeminggod.com)
Drawing from influences as diverse as billboard signs, classical portraiture and sculpture, to Japanese Manga comics and Hergé's Adventures of Tintin, Opie «paints» using a variety of media and technologies which enable him to make three - dimensional explorations of his subjects. (lissongallery.com)