ClipArt ETC
"Abatis consisting of trees lying parallel to each other with the branches pointing in the general direction of approach and interlaced. All leaves and small twigs should be removed and the stiff ends of branches pointed." — Moss, 1914

Abatis

"Abatis consisting of trees lying parallel to each other with the branches pointing in the general direction…

A hinged or sliding door in a floor or ceiling

Trap Door

A hinged or sliding door in a floor or ceiling

A thin, human-constructed barrier which separates two pieces of land or a house perimeter

Wire Fence

A thin, human-constructed barrier which separates two pieces of land or a house perimeter