Pronunciation: (gwī'ak), [key]
1. Also called guai'acum 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).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.