The Collaborative International Dictionary of English v.0.48:

Fungous \Fun"gous\, a. [L. fungosus: cf. F. fungueux.]
   1. Of the nature of fungi; spongy.
      [1913 Webster]

   2. Growing suddenly, but not substantial or durable.
      [1913 Webster]

WordNet (r) 3.0 (2006):

fungous
    adj 1: of or relating to fungi [syn: fungal, fungous]