hoarding(n = noun.artifact) billboard - large outdoor signboard;
is a kind of sign, signboard
1. A screen of boards inclosing a house and materials while builders are at work. [1913 Webster]
"Posted on every dead wall and hoarding." [1913 Webster]
2. A fence, barrier, or cover, inclosing, surrounding, or concealing something. [1913 Webster]
"The whole arrangement was surrounded by a hoarding, the space within which was divided into compartments by sheets of tin." [1913 Webster]
hoarding, n.
1 Brit. a large, usu. wooden, structure used to carry advertisements etc.
2 a board fence erected round a building site etc., often used for displaying posters etc.
Etymology:
obs. hoard f. AF h(o)urdis f. OF hourd, hort, rel. to HURDLE