/gwuy"ak/ , n.
1. Also called guaiacum gum, gum guaiac . a greenish-brown resin obtained from the guaiacum tree, esp. from Guaiacum officinale, used in varnishes, as a food preservative, and in medicine in various tests for the presence of blood.
2. guaiacum (def. 2).
[ 1550-60; see GUAIACUM ]