lignum vitae: small evergreen tree of Caribbean and southern Central America to northern South America; a source of lignum vitae wood, hardest of commercial timbers, and a medicinal resin
angiospermous tree: any tree having seeds and ovules contained in the ovary
free radical: an atom or group of atoms with at least one unpaired electron; in the body it is usually an oxygen molecule that has lost an electron and will stabilize itself by stealing an electron from a nearby molecule