paramüksoviiruste hulka kuuluv, eriti lastel kopsupõletikku ning muid hingamisteede infektsioone tekitav viirus, mis koekultuurides põhjustab mitmetuumaliste hiidrakkude (süntsüütsiumide) tekkimist, a pneumovirus (species Human orthopneumovirus of the genus Orthopneumovirus) that usually causes mild infections of the upper respiratory tract and lungs, that is spread through contact with respiratory droplets, and that is characterized especially by fever, cough, congestion, and runny nose but may progress to bronchiolitis and pneumonia especially in infants, the elderly, and immunocompromised individuals, infectious agent of the respiratory system that typically produces a mild coldlike illness but in susceptible individuals, particularly infants under six months of age, is a major cause of severe and potentially fatal lower respiratory disease