NOUN (2)

1. disease of grains; the entire head is a dusty mass of spores;

2. a smut fungus of the genus Ustilago causing a smut disease of grains in which the entire head is transformed into a dusty mass of spores;

WordNet (r) 3.0 (2006):

loose smut
    n 1: disease of grains; the entire head is a dusty mass of
         spores
    2: a smut fungus of the genus Ustilago causing a smut disease of
       grains in which the entire head is transformed into a dusty
       mass of spores