parainfluenza virus
noun
: any of several paramyxoviruses (genera Respirovirus and Rubulavirus) that are a frequent cause of infections (such as croup) of the lower respiratory tract especially in infants and children
Example Sentences
Recent Examples on the Web And that will be the same whether the virus being kept at bay is Covid-19, or RSV, or rhinovirus or parainfluenza virus. 
Maggie Fox, CNN, 26 Aug. 2021 Croup is usually caused by a viral infection, like parainfluenza virus, which can also cause laryngitis in adults, Gina Posner, M.D., a pediatrician at MemorialCare Orange Coast Medical Center in Fountain Valley, Calif., tells SELF. Korin Miller, SELF, 16 Oct. 2018
Maggie Fox, CNN, 26 Aug. 2021 Croup is usually caused by a viral infection, like parainfluenza virus, which can also cause laryngitis in adults, Gina Posner, M.D., a pediatrician at MemorialCare Orange Coast Medical Center in Fountain Valley, Calif., tells SELF. Korin Miller, SELF, 16 Oct. 2018 Word History
First Known Use
1959, in the meaning defined above
Medical Definition
parainfluenza virus
noun
para·in·flu·en·za virus ˈpar-ə-ˌin-flü-ˌen-zə- 
: any of several single-stranded RNA viruses (genera Respirovirus and Rubulavirus) of the family Paramyxoviridae that are associated with or responsible for some respiratory infections especially in children
called also parainfluenza