The precise meaning of the word in pro E101/479/30 is difficult to determine, as the term is merely listed among other tools. In this case it may refer to ‘a mason’s or marble-worker’s chisel’ (OED puncheon n.1 I.1), ‘Outil utilisé par les maçons pour dégrossir’ (DMF poinçon I.A.2), or even ‘Outil de forgeron : estampe à base concave servant à arrondir les têtes de clous’ (DMF poinçon I.A.3). It seems however, likely that a different implement is referred to here than the puncheon used by goldsmiths for marking their goods.

The sense ‘large barrel’ probably derives from the practice of marking barrels of approved capacity with an official stamp. The FEW suggests that the expression may at first have been tonneau à poinçon (‘stamped barrel’), reduced to a single word (FEW 9,584a; see also OED etymology of puncheon n.2).