noun
1. : a decay of seasoned timber caused by certain fungi (as the house fungi and some polypores) that consume the cellulose of wood leaving a mere soft skeleton that is readily reduced to powder
2. : a rot of plant tissue in which the affected areas are not soft and wet but dry and often firmer than normal or more or less mummified: as
a. : decay of standing timber involving such rot and caused chiefly by polypores
b. : any of various fungous diseases of cultivated plants involving such rot especially of roots, tubers, and fruits and caused usually by fungi of the genera Fusarium, Diaporthe, Diplodia, or Volutella
3. : a fungus causing dry rot
4. : deterioration and decay from within caused by apathy or by resistance to new and vitalizing forces ; also : the cause of such decay
warned against the dry rot which infects art when it becomes more interested in itself than in what it is saying — Saturday Review
in a representative democracy lack of strong conviction in the electorate is a form of dry rot capable of eventually destroying the whole fabric — G.W.Johnson