Lewis Short
ulmĭtrĭba (noun M) : vox hibrida, from ulmus and τρίβω, tero, an elm-rubber, i. e.
* One that wears out elms, is often beaten with elm-rods, a term of abuse, Plaut. Pers. 2, 4, 7; cf. ulmus.
Charlton T. Lewis, Charles Short, A Latin Dictionary