noun \ˈg(w)ī-ə-kəm\

Definition of GUAIACUM

capitalized : a genus (family Zygophyllaceae) of tropical American trees and shrubs having pinnate leaves, usually blue flowers, and capsular fruit
: any tree or shrub of the genus Guaiacum
: a resin with a faint balsamic odor obtained as tears or masses from the trunk of either of two trees of the genus Guaiacum (G. officinale or G. sanctum) used formerly in medicine as a remedy for gout or rheumatism and now in various tests (as for peroxidases or bloodstains) because of the formation of a blue color on oxidation—see guaiac test

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