A long handle, usually made of wood, that attaches to the top of sailboat’s rudder or rudder post to turn the rudder for steering. The boat turns in the direction opposite that in which the tiller is pushed: to turn right (to starboard), push the tiller left (to port). Tillers are more commonly used on smaller sailboats because it can take much force to move the larger rudder of a big boat with a tiller. All sailboats are steered either with a tiller or a wheel.
The term tiller is also used for the steering arm of small outboard engines.