- a rope or rod along a ship's yard, to which the edge of a sail is fastened
- a rope or rod that runs up and down a ship's mast, along which the yard moves when being hoisted or lowered
Origin of jackstayjack- + stay
- A stay for racing or cruising vessels used to steady the mast against the strain of the gaff.
- A rope, rod, or batten along the upper side of a yard, gaff, or boom to which a sail is fastened.
- A rope or rod running vertically on the forward side of the mast on which the yard moves.