Lewis & Short

purgāmen, ĭnis, n. [purgo].

  1. I. What was annually swept or washed from the temple of Vesta, i. e. the dirt or filth swept out, the sweepings, offscourings, Ov. F. 6, 713 and 227; v. stercus.
  2. II. A means of purgation, purification, or expiation: caedis, Ov. M. 11, 409: mali, id. F. 2, 35; 2, 23: mentis, id. M. 15, 327: aquae, i. e. baptism, Prud. στεφ. 6, 30.
  3. III. Purity, clearness, Prud. Cath. 7, 80.