Look up viral in Wiktionary, the free dictionary.
The adjective or adverb viral and the noun virality may refer to any viral phenomenon, that is, an object or pattern that is able to induce some agents to replicate it, resulting in many copies being produced and spread around. For example, virality relating to social, cultural, emotional, and affective contagions that spread through socio-technical networks.
In medical terminology "viral" means pertaining to a virus.
More specifically, the terms may be used in reference to:
A biological virus,
A computer virus,
Viral marketing, the use of existing social networks to spread a marketing message,
Viral phenomenon, relating to contagion theory or the "virality" of network culture,
A viral video, a video that quickly attains a high popularity