A yarn made of two or more continuous monofilaments held together by twist or otherwise. Filler- In woodworking, any substance used to fill the holes and irregularities in cleaned or standard surfaces to decrease in the porosity of the surface before applying finish coatings. wooded filler -- for cracks, knot holes, worm holes, etc. Usually a commercial wood putty, plastic wood, or other materials mixed to the consistency of putty. A wood filler may also be mixed on the job using sanding dust from the final sanding, or other suitable material, mixed with sealer, or finish.