Any one of a class of yellowish brown solid inflammable substances, of vegetable origin, which are nonconductors of electricity, have a vitreous fracture, and are soluble in ether, alcohol, and essential oils, but not in water; specif., pine resin (see Rosin). Note: Resins exude from trees in combination with essential oils, gums, etc., and in a liquid or semiliquid state. ...