viral

/ˈvaɪrəl/ adjective INTERNET, MARKETING

Definition

› spreading or becoming popular very quickly through communication from one person to another, especially on the internet: viral ad/advertising In the future, he predicts, viral ads will offer even more participation. All their clever targeted viral campaigning may ultimately be less effective than good old mass marketing. From viral video to text-message campaigns and avatar sales reps, futuristic marketing tools are quickly becoming commonplace.

go viral › to become very popular very quickly: There's no surefire way to make a given video go viral, even if it features a celebrity.

(Definition of viral adjective from the Cambridge Business English Dictionary © Cambridge University Press)