Lewis Short
frĕmor (noun M) : fremo
* A low roaring, rushing, murmuring (poet. and in postclass. prose for fremitus): arma sonant, fremor oritur, Poët. ap. Varr. L. L. 6, § 67 Müll.: variusque per ora cucurrit Ausonidūm fremor,Verg. A. 11, 297; Arn. 1, 32.— In plur.: leonum indignati fremores,App. Flor. p. 358, 4.
Charlton T. Lewis, Charles Short, A Latin Dictionary