mastum Save DMLBS 1 mastum [ME mast] , mast (measure of weight, usu. 2.5 lbs.). 1509 de navi Petri Busse ij mandes cum ij ~is ambr[e] ‥ iiij libris yvery bedes (KR AcCust) EEC 572. 2 mastum v. mastus