Yardarm

1. (Naut.) Either half of a square-rigged vessel's yard{6}, from the center or mast to the end.
2. (Naut.) The portion of a yard{6} outboard of the slings, often called the outer quarter.

Ships are said to be yardarm and yardarm when so near as to touch, or interlock yards.

A yard{6} is considered to have four unequal quarters, two quarters extending from the mast to the slings on each side, and two smaller outer quarters outboard of the slings.