resin

n. [ F. résine, L. resina; cf. Gr. "rhti`nh Cf. Rosin.] 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). [1913 Webster]

☞ Resins exude from trees in combination with essential oils, gums, etc., and in a liquid or semiliquid state. They are composed of carbon, hydrogen, and oxygen, and they consist primarily of polymerized small molecules having carboxylic groups. Copal, mastic, guaiacum, and colophony or pine resin, are some of them. When mixed with gum, they form the gum resins, like asafetida and gamboge; mixed with essential oils, they form balsams, or oleoresins. They are also used in making varnishes. [1913 Webster]

2. Any of various polymeric substance resembling the natural resins[1], prepared synthetically; -- they are used, especially in particulate form, in research and industry for their property of specifically absorbing or adsorbing substances of particular types; they are especially useful in separation processes such as chromatography; as, an ion-exchange resin. [PJC]

Highgate resin (Min.), a fossil resin resembling copal, occuring in blue clay at Highgate, near London. --
Resin bush (Bot.), a low composite shrub (Euryops speciosissimus) of South Africa, having smooth pinnately parted leaves and abounding in resin. [1913 Webster]