The meaning of VIRAL is of, relating to, or caused by a virus. How to use viral in a sentence. What is a viral infection? Viral infections are illnesses you get from tiny organisms that use your cells to make more copies of themselves (viruses). Viral infections commonly cause respiratory and digestive illnesses, but viruses can also infect most other parts of your body. viral adjective (INTERNET) used to describe something that quickly becomes very popular or well known by being published on the internet or sent from person to person by email, phone, etc.: The word Viral means "relating to viruses " (small infectious agents). It may also refer to: Memetic behavior likened that of a virus, for example: A viral film clip, story, or message is one that spreads quickly because people share it on social media and send it to each other. 1. Of, relating to, or caused by a virus. 2. Of or relating to the rapid propagation of information, ideas, or trends by means of social networks rather than conventional mass media: viral marketing. Nov 5, 2017 · used to describe a piece of information, a video, an image, etc. that is sent rapidly over the internet and seen by large numbers of people within a short time. Within 24 hours, the video went viral on YouTube and Facebook. Definition of viral adjective in Oxford Advanced Learner's Dictionary.