- either of two tropical American trees, Guaiacum officinale or G. sanctum, of the caltrop family, having very hard, heavy wood.
- the wood of such a tree, used for making pulley blocks, mallet heads, bearings, etc.
- any of several other trees yielding a similar hard wood.
- either of two zygophyllaceous tropical American trees, Guaiacum officinale or G. sanctum, having blue or purple flowers
- the heavy resinous wood of either of these trees, which is used in machine bearings, casters, etc: formerly thought to have medicinal properties