Lewis Short
spissāmentum (noun N) : spisso, that which is used to compress or stop up any thing
* A stopple, plug (post-Aug.): firmiori (quam cera) spissamento opus est,Sen. Ep. 31, 1: spissamento facto de harundinum foliis,Col. 12, 49, 4: faeniculi,id. 12, 49, 4, § 6; 12, 7, 3; 12, 9, 2.
Charlton T. Lewis, Charles Short, A Latin Dictionary