hoayacan.

Headword: 
hoayacan.
Principal English Translation: 

a plant (also called a "blue tree"), possibly a species of box wood, that could be made into a cure for the "French malady" or the "French disease" (syphilis) (Valley of Mexico, 1570–1587)
The Mexican Treasury: The Writings of Dr. Francisco Hernández, ed. Simon Varey, transl. Rafael Chabrán, Cynthia L. Chamberlin, and Simon Varey (Stanford: Stanford University Press, 2000), 121–22.

Orthographic Variants: 
guayacan, huayacan
Attestations from sources in English: 

"This tree is of medium height, with a woody trunk, lean and spiny...The heart is not bitter. Its effects are used to cure the French malady and chronic diseases of the head, chest, stomach, gall bladder, kidneys, and pains in the other parts of the body." (Central Mexico, 1571–1615)
The Mexican Treasury: The Writings of Dr. Francisco Hernández, ed. Simon Varey, transl. Rafael Chabrán, Cynthia L. Chamberlin, and Simon Varey (Stanford: Stanford University Press, 2000), 122.

themes: 
Health, Sickness, Wellness, Medicine
Plants, Trees, Flora
Wood, wooden material