matrass \ma*trass"\, n. [F. matras; perh. so called from its long narrow neck; cf. OF. matras large arrow, L. materis, mataris, matara, a Celtic javelin, pike; of Celtic origin.] (Chem.) A round-bottomed glass flask having a long neck; a bolthead. [1913 Webster]
Bolthead \Bolt"head`\, n. 1. (Chem.) A long, straight-necked, glass vessel for chemical distillations; -- called also a {matrass} or receiver. [1913 Webster] 2. The head of a bolt. [1913 Webster]