par·a·myx·o·vi·rus 
(păr′ə-mĭksə-vī′rəs)
(păr′ə-mĭksə-vī′rəs)n. pl. par·a·myx·o·vi·rus·es
Any of a family of single-stranded RNA viruses including the respiratory syncytial virus, parainfluenza viruses, and viruses that cause measles and mumps.