(intransitive) Tack; to cause to turn into the wind and through the other side ending with a full 180 degree turn.

plural of headmistress-ship

The position of a headmistress. / The tenure of a headmistress.

(nautical) The entire crew of a ship, including the officers / (nautical, possibly nonstandard) All of the occupants of a ship, including crew and passengers.

(of a missile) fired from ship at a target on the ground

(of a missile) fired from the ground at a target ship

(of a missile) fired from a an aircraft in flight to a ship

(of a missile) fired from a ship at an aircraft in flight, or at an incoming missile

(dated, nautical) An agent who has the authority to repair and outfit a particular ship

(nautical, literally) To leave or forsake a ship due to its impending doom. / (by extension) To leave a person or organization when things become difficult.