Lewis Short
(adjective) : frĕmĕbundus, a, um, fremo
* Making a low roaring, growling, snorting, muttering, murmuring (poet.): tanta moles (Argo), Att. ap. Cic. N. D. 2, 35, 89: illapsu (elephantorum),Sil. 3, 463: tum vero praeceps (Achilles) curru fremebundus ab alto Desilit,Ov. M. 12, 128.
Charlton T. Lewis, Charles Short, A Latin Dictionary