(Science: chemical) mineral tar, a kind of soft native bitumen. Tar board, a strong quality of millboard made from junk and old tarred rope. Tar water. A cold infusion of tar in water, used as a medicine. The ammoniacal water of gas works. Wood tar, tar obtained from wood. It is usually obtained by the distillation of the wood of the pine, spruce, or fir, and is used in varnishes, cements, and to render ropes, oakum, etc, impervious to water.
Origin: OE. Terre, tarre, AS. Teru, teoru; akin to D. Teer, G. Teer, theer, Icel. Tjara, Sw. Tjara, Dan. Tiaere, and to E. Tree. 63. See Tree.