Exact historical dictionary sense
Size in Webster's 1913 dictionary
The 1913 record labels size as noun. Its source-bounded etymology and selected historical definition appear below.
[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.]
Cross-verified historical senseIn Webster's Revised Unabridged Dictionary (1913), "size" is labeled noun. Its etymology is recorded as: "[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.]" The selected historical definition says: "A thin, weak glue used in various trades, as in painting, bookbinding, paper making, etc."