Lewis & Short

serpĕrastra (serpĭr-), ōrum, n. [perh. from serpo-rastrum, creepingsplints], knee-splints or knee-bandages for straightening the crooked legs of children.

  1. * I. Lit.: pueris in geniculis alligare, Varr. L. L. 9, § 11 Müll.
  2. * II. Transf., humorously of officers, who hold the soldiers in check: de serperastris cohortis meae nihil est quod doleas, Cic. Att. 7, 3, 8.