a flexible strip (wood or rubber) used in drawing curved lines
"The artist carefully placed the wooden spline along the parchment to guide her pen as she drew the sweeping curve of the river."
Long thin piece of metal or wood.
"The carpenter drove a long wooden spline into the groove to hold the two pieces of molding together tightly."
To smooth (a curve or surface) by means of a spline.
"The engineer used a flexible metal strip to manually splay the curved edge of the wooden frame before gluing it in place."