The Collaborative International Dictionary
Guaiacum \Gua"ia*cum\, n. [NL., fr. Sp. guayaco, from native name in Haiti.]
(Bot.) A genus of small, crooked trees, growing in tropical America.
The heart wood or the resin of the Guaiacum officinale or lignum-vit[ae], a large tree of the West Indies and Central America. It is much used in medicine. [Written also guaiac.]
Lignum-vitae \Lig"num-vi"tae\ (l[i^]g"n[u^]m v[imac]"t[=e]), n. [L., wood of life; lignum wood + vita, genitive vit[ae], life.] (Bot.) A tree ( Guaiacum officinale) found in the warm latitudes of America, from which the guaiacum of medicine is procured. Its wood is very hard and heavy, and is used for various mechanical purposes, as for the wheels of ships' blocks, cogs, bearings, and the like. See Guaiacum.
Note: In New Zealand the Metrosideros buxifolia is called lignum-vit[ae], and in Australia a species of Acacia. The bastard lignum-vit[ae] is a West Indian tree ( Sarcomphalus laurinus).
Wikipedia
Guaiacum officinale, commonly known as roughbark lignum-vitae, guaiacwood or gaïacwood, is a species of tree in the caltrop family, Zygophyllaceae, that is native to the Caribbean and the northern coast of South America.