guai·​a·​cum ˈgwī-ə-kəm How to pronounce guaiacum (audio) ˈgī- How to pronounce guaiacum (audio)
: 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

Examples of guaiacum in a Sentence

Recent Examples on the Web The old guaiacum test was very clumsy and uncertain. Roy Schwartz, CNN, 20 May 2022

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'guaiacum.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

Dictionary Entries Near guaiacum

Cite this Entry

“Guaiacum.” Dictionary, Merriam-Webster, Accessed 15 Jun. 2024.

Medical Definition


guai·​a·​cum ˈg(w)ī-ə-kəm How to pronounce guaiacum (audio)
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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