an astringent substance extracted from various S Asian plants (genus Uncaria) of the madder family, chewed with the betel nut: used in tanning and dyeing and, formerly, in medicine
See gambier in American Heritage Dictionary 4
also gam·bir(gămˈbîr)
noun
A resinous astringent extract obtained from the leaves of a woody vine (Uncaria gambir) of Malaysia and Indonesia, used medicinally and in tanning and dyeing.