The Collaborative International Dictionary of English v.0.48:

Lum \Lum\ (l[u^]m), n. [W. llumon chimney, llum that shoots up
   or ends in a point.]
   1. A chimney. [Prov. Eng. & Scot.] --Burns.
      [1913 Webster]

   2. A ventilating chimney over the shaft of a mine.
      [1913 Webster]

   3. A woody valley; also, a deep pool. [Prov. Eng.]
      [1913 Webster] Lumachel