stabilizer

Short definition from Wiktionary

Noun

1. 1
   Any person or thing that brings stability: Any substance added to something in order to stabilize it, as for example a fuel additive that prolongs the shelf life of petrol.
2. 2
   Any person or thing that brings stability: An additional wheel on a bicycle to keep it upright to assist a learner.
3. 3
   Any person or thing that brings stability: A gyroscopically controlled fin or similar device that prevents the excess rolling of a ship in rough seas.
4. 4
   Any person or thing that brings stability: An airfoil that stabilizes the flight of an aircraft or missile.
5. 5
   Any person or thing that brings stability: A piece of backing fabric used in embroidery.
6. 6
   For a group operating on a set and an element x of the set, the set of all group elements fixing x.