The resin of Guaiacum officinale or G. sanctum (family Zygophyllaceae); a nauseant, diaphoretic, stimulant, and reagent in testing for occult blood. SYN: g. gum. [Sp. guayaco, imitating the native Carib name]
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guai·ac (gwiґək) a resin from the wood of the tropical trees Guaiacum officinale and G. sanctum, used as a reagent in tests for occult blood and formerly in the treatment of rheumatism.Medical dictionary. 2011.