Viral (adjective)

1. Of or relating to a virus.
2. Spreading rapidly and widely from person to person, especially through the internet.

Origin:

From latin virus meaning "poison, venom".

Examples:

1. The viral infection spread quickly throughout the office.
2. The video of the dancing baby became viral on the internet.
3. Viral marketing is a strategy to spread a message through social networks.
4. Viral diseases can be transmitted through blood transfusions.
5. The viral post had over a million shares on social media.