a fast-drying oil derived from the seeds of the tung tree, used in place of linseed oil in paints, varnishes, etc. for a more water-resistant finish
See tung oil in American Heritage Dictionary 4
(tŭng)
noun
A yellow or brownish oil extracted from the seeds of the tung tree and used as a drying agent in varnishes and paints and for waterproofing. Also called Chinawood oil.