"Tri-vision billboard" means a type of billboard having a series of three-sided rotating slats arranged side by side, either horizontally or vertically, which are rotated by an electric-mechanical process, capable of displaying a total of three separate and distinct messages, one message at a time. (Added by Ord. 13-073, Dec. 11, 2013, Eff date Dec. 26, 2013; Amended by Ord. 13-074, Dec. 11, 2013, Eff date Dec. 26, 2013).