A longitudinal strip projecting from an object to strengthen it, or to enter a channel in another object and thereby prevent displacement sideways but permit motion lengthwise; a spline.
One of the two shims of the three-piece stone-splitting tool known as plug and feather or plug and feathers; the feathers are placed in a borehole and then a wedge is driven between them, causing the stone to split.
To streamline the blades of an aircraft's propeller by rotating them perpendicular to the axis of the propeller when the engine is shut down so that the propeller does not windmill during flight.