The Collaborative International Dictionary of English v.0.48:

Favus \Fa"vus\, n. [L., honeycomb.]
   1. (Med.) A disease of the scalp, produced by a vegetable
      parasite.
      [1913 Webster]

   2. A tile or flagstone cut into an hexagonal shape to produce
      a honeycomb pattern, as in a pavement; -- called also
      favas and sectila. --Mollett.
      [1913 Webster]