Jamb
Top, sides, studs, frame and trim of a door, window or other opening.
Jig
A device used to make special cuts, guide a tool, or aid in woodworking operations.
Jig saw
a power tool that cuts by moving a blade up and down as it is guided through the cut.
Joinery
Connecting or bonding two pieces of wood.
Jointer
A woodworking machine designed to straighten and square a board's edge.