The term 'spline' is a type of tool used in carpentry and woodworking. It is a thin strip of wood or metal that is curved or bent to fit the contours of a surface. The two crossword solutions for this term are 'LATH' and 'SLAT', both of which are four letters long. LATH is a thin strip of wood or metal used as a backing for plaster, stucco, or tile. SLAT is a thin strip of wood or metal used as a support for a bed or chair. Both LATH and SLAT are commonly used in carpentry and woodworking, and can be used to create a spline.