splines

Long thin piece of metal or wood.

A rectangular piece that fits grooves like key seats in a hub and a shaft, so that while the one may slide endwise on the other, both must revolve together.

A flexible strip of metal or other material, that may be bent into a curve and used in a similar manner to a ruler to draw smooth curves between points.

Any of a number of smooth curves used to join points.

A strip of wood or other material inserted into grooves in each of two pieces of wood to provide additional surface for gluing.

Ridges or teeth on a drive shaft that mesh with grooves in a mating piece and transfer torque to it, maintaining the angular correspondence between them.