billboards is a form of:

Billboard



noun
1.
(a hoarding, a board, usually set up outdoors to display public notices or advertising) ផ្ទាំងប្រកាស, ក្ដារបិទប្រកាស
ENGLISH MEANING
noun
1.
A piece of thick plank, armed with iron plates, and fixed on the bow or fore channels of a vessel, for the bill or fluke of the anchor to rest on.
2.
A flat surface, as of a panel or of a fence, on which bills are posted; a bulletin board.