- any of several tropical American trees or shrubs belonging to the genus Guaiacum of the caltrop family; lignum vitae.
- the hard, heavy wood of such a tree; guaiac.
- resin obtained from such a tree; guaiac.
- any tropical American evergreen tree of the zygophyllaceous genus Guaiacum, such as the lignum vitae
- the hard heavy wood of any of these trees
- a brownish resin obtained from the lignum vitae, used medicinally and in making varnishes
