Size (?), n. [OIt. sisa glue used by painters, shortened fr. assisa, fr. assidere, p. p. assiso, to make to sit, to seat, to place, L. assidere to sit down; ad + sidere to sit down, akin to sedere to sit. See Sit, v. i., and cf. Assize, Size bulk.] 1. A thin, weak glue used in various trades, as in painting, bookbinding, paper making, etc.
2. Any viscous substance, as gilder's varnish.