In sailing, a stay is a strong cable, wire, or rod (part of the standing rigging) that supports a mast from forward or aft to prevent it from moving or falling. Staysails are triangular sails attached to these lines, while being "in stays" refers to a vessel being head-to-wind and stalling during a tack.

Key Stay Types and Definitions:
Forestay/Headstay: A stay that runs from the mast down to the bow of the boat, supporting the mast and often carrying a headsail.

Backstay: A stay running from the mast to the stern (back) of the boat to stop it from falling forward.

Staysail: A sail whose luff is attached to a stay (often an inner forestay), commonly used in heavy wind or on cutters.

Running Backstay/Checkstay: Adjustable stays that provide extra support, particularly when using a staysail or in high winds, to stop the mast from pumping.

Common Phrases:
In Stays: When a boat is head-to-wind and fails to complete a tack, stalling in the middle of the turn.

Miss Stays: Failing to successfully change tack, resulting in the boat falling back onto its original course.

Passing the Staysail: The act of moving the staysail to the other side during a tack.