Source : Webster's Revised Unabridged Dictionary (1913)

Copal \Co"pal\ (k[=o]"pal; 277), [Sp., fr. Mexican copalli, a
   generic name of resins. --Clavigero.]
   A resinous substance flowing spontaneously from trees of
   Zanzibar, Madagascar, and South America ({Trachylobium
   Hornemannianum}, {T. verrucosum}, and {Hymen[ae]a
   Courbaril}), and dug from earth where forests have stood in
   Africa; -- used chiefly in making varnishes. --Ure.

Source : WordNet®

copal
     n : a brittle aromatic resin used in varnishes