The Collaborative International Dictionary of English v.0.48:

Gambier \Gam"bier\, n. [Malayan.]
   (a) The inspissated juice of a plant (Uncaria Gambir)
       growing in Malacca. It is a powerful astringent, and,
       under the name of Terra Japonica, is used for chewing
       with the Areca nut, and is exported for tanning and
       dyeing.
   (b) Catechu. [Written also gambeer and gambir.]
       [1913 Webster]