[Fr., from L. resinaJ] A half liquid substance, that flows from trees. Resins are made up of carbon, hydrogen, and oxygen, and are probably the essential oils of the plants oxidized by the oxygen of the air. They dissolve in alcohol and ether and volatile oils, but not in water, like gums. Copal, lac, mastic, and benzoin are hard resins; turpentine and copaiba are soft resins. The common resin of commerce exudes from the pine tree, and is largely used in making varnishes and in several medicines.