Lewis Short
sūrus (noun M) :
* A branch, a stake, Varr. L. L. 10, § 73 Müll.: surum dicebant, ex quo per deminutionem fit surculus. Ennius: unus surus surum ferret, tamen defendere possent,Fest. p. 299 ib. (cf. Enn. Ann. v. 516 Vahl.); cf. crebrisuro.
Charlton T. Lewis, Charles Short, A Latin Dictionary