aspergillosis n 1: severe respiratory disease of birds that takes the form of an acute rapidly fatal pneumonia in young chickens and turkeys [syn: {aspergillosis}, {brooder pneumonia}] 2: an opportunistic infection by a fungus of the genus Aspergillus; characterized by inflammation and lesions of the ear and other organs 3: disease especially in agricultural workers caused by inhalation of Aspergillus spores causing lumps in skin and ears and respiratory organs