SPLINE, to provide with a key to make a wheel and shaft revolve [v]
A rectangular key fitting into grooves in the hub and shaft of a wheel, esp. one formed integrally with the shaft that allows movement of the wheel on the shaft
A corresponding groove in a hub along which the key may slide
A slat
SPLINE, to provide with a spline (a key that connects two rotating mechanical parts) [v]
A flexible wood or rubber strip used esp. in drawing large curves
A continuous curve constructed so as to pass through a given set of points and have a certain number of continuous derivatives