jointer

1. A machine or tool used in making joints.
2. A tool used to cut grooves indicating the joints in cement.
3. A triangular attachment to a plow used in covering trash or refuse.

1. A metal tool used to cut a joint partly through fresh concrete.
2. In masonry, a tool for filling the cracks between courses of bricks or stones.
3. In masonry, a bent strip of iron inserted into a wall to strengthen a joint.
4. In carpentry, a long plane, esp. used to square the edges of boards or veneer so that they will make a close joint with other pieces.

The noun has one meaning:

Meaning #1: a long carpenter's plane used to shape the edges of boards so they will fit together
  Synonyms: jointer plane, jointing plane, long plane