Lewis & Short

2. casso (caso), avi, atum, 1, v. n., rare collat. form of quasso (only in Plautus), to shake, waver: ubi bacchabatur aula, cassabant cadi, Plaut. Mil. 3, 2, 41; cf. v. 37: capitibus cassantibus, id. Bacch. 2, 3, 71; cf. quasso, II.