a small, sturdy, triangular sail rigged fore and aft on a gaff, esp. one used in place of the mainsail in stormy weather
Origin of trysail; from naut. phrase a try, the position of lying to in a storm
A small fore-and-aft sail hoisted abaft the foremast and mainmast in a storm to keep a ship's bow to the wind.
Origin of trysailFrom obsolete try, a lying to, heaving to.