SIZE, a general term for bulk or quantity; also an agglutinant consisting of undried glue. The two words, though they are so widely separate in meaning, are by etymology the same. " Size" (Lat. assidere, to sit down to) is a shortened form of " assize," through the French and Italian respectively. The O. Fr. assis, assise, and Eng. " assize," meant a sitting of a deliberative or other body; hence decree, ordinance of such a body, specifically of such as regulated weights, measures, prices; thus it came to mean a standard of measure price, quantity thus fixed, and so merely quantity or measure, in which sense it remains in the shortened form " size." In the sense of an agglutinant, " size " is an adaptation of Ital. sisa, a shortened form of assisa (Lat. assidere), and seems to have meant by derivation " that which painters use to make the colours sit well or suitably."
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)