Lewis & Short

pūs, pūris, n. [Sanscr. pu-, to be fetid; Gr. πῦον, πύθω, etc.].

  1. I. Lit., white and viscous matter of a sore, pus, Cels. 5, 26, 20; 5, 28, 8.
    In plur.: pura, Plin. 24, 16, 92, § 145; 35, 6, 21, § 38.
  2. II. Transf., as designation of a malicious person: Titus Lucius … febris, senium, vomitum, pus, Lucil. ap. Non. 2, 31: Rupili pus atque venenum, Hor. S. 1, 7, 1.