n. 1 a gum or resin exuded from the bark of the mastic tree, used in making varnish. 2 (in full mastic tree) the evergreen tree, Pistacia lentiscus, yielding this. 3 a waterproof filler and sealant used in building. 4 a liquor flavoured with mastic gum.
[ ME f. OF f. LL mastichum f. L mastiche f. Gk mastikhe, perh. f. mastikhao (see MASTICATE) with ref. to its use as chewing-gum ]