The most common and most likely answer to this crossword clue is the 5 letter word VIRAL
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The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does VIRAL mean?
VIRAL noun- A video, image or text spread by "word of mouth" on the internet or by e-mail for humorous, political or marketing purposes.
- Of or relating to a biological virus.
- Caused by a virus.
- Of the nature of an informatic virus; able to spread copies of itself to other computers.
- Spread by word of mouth, with minimal intervention in order to create buzz and interest.
- (of an image, video, piece of information, etc.) circulated rapidly and widely from one Internet user to another.