Used in the Strassburg Constitutions, and other German works of the Middle Ages, as equivalent to the modern Freemasonry. Kloss translates it by Masonhood. Lessing derives it from mosa, Anglo Saxon, a table, and says it means a Society of the Table. Nicolai deduces it from the Low Latin masTanya, which means both a club and a key, and says it means an exclusive society or club, and so, he thinks, we get our word Masonry. Krause traces it to mas mase, food or a banquet. It is a pity to attack these speculations, but we are inclined to look at Masonry as simply a corruption of the English Masonrie.
the source: Mackey’s Encyclopedia of Freemasonry