
1) Chinese invention 2) Varnish ingredient 3) Vegetable oil
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https://www.crosswordclues.com/clue/tung-oil

Tung oil or China wood oil is a drying oil obtained by pressing the seed from the nut of the tung tree (Vernicia fordii). As a drying oil, tung oil hardens (dries) upon exposure to air. The resulting coating is transparent and plastic-like; a property which is exploited in most of its applications such as wood finishing, as well as in the composit...
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http://en.wikipedia.org/wiki/Tung_oil

pale-yellow, pungent drying oil obtained from the seeds of the tung tree. On long standing or on heating, tung oil polymerizes to a hard, waterproof ... [1 related articles]
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http://www.britannica.com/eb/a-z/t/91

The Oil of the nut of the tung tree. Generally used in fine wood finishing.
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http://www.encyclo.co.uk/local/22428

Tung oil (also known as Kukrui oil and China wood oil) is an oil obtained from the seed pods of several varieties of the aleurites or tung tree native to China. Tung oil is pale amber in colour, dull, with an unpleasant smell and taste. It is one of the best drying oils and was used in quick-drying paints and marine varnishes.
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http://www.probertencyclopaedia.com/browse/GT.HTM

[
n] - a yellow oil obtained from the seeds of the tung tree
Found on
http://www.webdictionary.co.uk/definition.php?query=tung%20oil
Chinese wood oil noun a yellow oil obtained from the seeds of the tung tree
Found on
https://www.encyclo.co.uk/local/20974

Oil used in paints and varnishes, obtained from tung trees native to China. (Genus
Aleurites, family Euphorbiaceae.)
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https://www.encyclo.co.uk/local/21221

a yellow drying oil derived from the seeds of a tung tree, Aleurites fordii, used in varnishes, linoleum, etc.
Found on
https://www.infoplease.com/dictionary/tung-oil
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