any of various RNA-containing viruses that are similar to but larger than the myxoviruses, including the viruses that cause mumps, measles, parainfluenza, and Newcastle disease.
A genus of viruses that contain RNA and are similar to but larger and more variable in size than the related myxovirus; it includes the Sendai virus, the parainfluenza viruses, and the viruses that cause measles and mumps.
