worm fence

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A fence of crossed rails supporting one another and forming a zigzag pattern. Also called snake fence, Virginia fence.

GNU Webster's 1913

1. n. a zigzag fence composed of rails crossing one another at their ends; -- called also snake fence, or Virginia rail fence.
2. n. See under Fence.

WordNet 3.0

1. n. rail fence consisting of a zigzag of interlocking rails