Lewis Short
dūmus | dusmus (noun M) : (old form , v. dumosus), , dusmus for densimus, from densus
* A thorn-bush, bramble, Cic. Tusc. 5, 23, 65; Verg. G. 3, 315; 338; 4, 130; id. A. 4, 526 et saep.
Charlton T. Lewis, Charles Short, A Latin Dictionary