a (usually) cross-section of a branch that is imbedded in lumber or other wood product —note 1. a knot may be regarded as either a decorative feaure or a defect —note 2. a sound knot (live knot, tight knot) occurs if the branch was living when the tree was cut; a loose knot, so called because the knot commonly falls out of the lumber, occurs if the branch was dead when the tree was cut —see sucker knot This definition last updated 10/28/2008