guaiacum

noun

guai·a·cum ˈgwī-ə-kəm

ˈgī-

: any of a genus (Guaiacum) of the caltrop family of tropical American evergreen trees and shrubs having pinnate leaves, usually blue flowers, and capsular fruit

: the hard greenish-brown wood of a guaiacum (especially Guaiacum officinale)

: a resin with a faint balsamic odor that is obtained from the trunk of two guaiacums (G. officinale and G. sanctum) and often used as a clinical reagent

Word History

Etymology

New Latin, from Spanish guayaco, from Taino guayacan

First Known Use

1553, in the meaning defined at sense 1

Time Traveler

The first known use of guaiacum was in 1553

See more words from the same year

Cite this Entry

Style

“Guaiacum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/guaiacum. Accessed 6 Jul. 2026.

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Medical Definition

guaiacum

noun

guai·a·cum ˈg(w)ī-ə-kəm

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