res·in / ˈrezən/ • n. a sticky flammable organic substance, insoluble in water, exuded by some trees and other plants (notably fir and pine).Compare with gum¹ (sense 1). ∎  (also syn·the·tic res·in) a solid or liquid synthetic organic polymer used as the basis of plastics, adhesives, varnishes, or other products.• v. (res·ined, res·in·ing) [tr.] [usu. as adj.] (resined) rub or treat with resin: resined canvas.DERIVATIVES: res·in·ous / ˈrezənəs/ adj.

resin An exudate of tree wood or bark, liquid but becoming solid on exposure, consisting of a complex of terpenes and similar compounds. It is characteristic of some families, e.g. Dipterocarpaceae, or groups, e.g. the conifers. In many cases it is of economic value for varnishes, etc. It is produced in specialized cells.

resin (rosin) Artificial or natural polymer that is generally viscous and sticky. Artificial resins include polyesters and epoxies and are used as adhesives and binders. Natural resins are secreted by various plants. Oleoresin, secreted by conifers, is distilled to produce turpentine; rosin remains after the oil of turpentine has been distilled off.

resin A naturally occurring acidic polymer secreted by many trees (especially conifers) into ducts or canals. Resins are found either as brittle glassy substances or dissolved in essential oils. Their functions are probably similar to those of gums and mucilages, i.e. protective.

resin, rosin adhesive substance secreted by plants. XIV. ME. recyn, resyn, rosyn, rosine — L. resīna and medL. rosīna, of unkn. orig.
So resinous XVII. — F. — L.