Definition of viroid in US English:



  • An infectious entity affecting plants, smaller than a virus and consisting only of nucleic acid without a protein coat.

    • ‘A single viroid was found to cause more than a dozen different plant diseases.’
    • ‘Prions do not contain DNA or RNA as do fungi, bacteria, viruses, viroids, or any other previously known infectious entities.’
    • ‘They include animals, insects, and nematodes (while vine diseases include the microbes bacteria, fungi, phytoplasma, viroids, and virus).’
    • ‘In 1971, ARS researchers determined that a viroid was the cause of potato spindle tuber disease, which previously had been identified as a virus.’
    • ‘Fast, accurate tests, based on antibody testing technology, were developed for trichinosis in pigs; for anaplasmosis, a costly parasitic disease in cattle; and for plant viruses and viroids.’