Lewis & Short

mūsĭmo or musmo, ŏnis, m., = μούσμων,

  1. I. an animal of Sardinia, prob. the muflone, from which we have the tame sheep, Plin. 8, 49, 75, § 199.
  2. II. Transf.: musimones asini, muli, aut equi breves. Lucil. lib. sexto: pretium emit, qui vendit equum musimonem (i. e. a stallion). Cato Deletorio: asinum aut musimonem aut arietem, Non. 137, 22 sq.; cf. Serv. Verg. G. 3, 446.