[countable noun] the fans of a particular person, team, TV show, etc. considered together as a community.

This US comedy show has a really strong fandom.

[uncountable noun]
the state of being a fan of somebody/something.

The book takes a fascinating look at sports fandom in the United States.

my 17 years of football fandom

Readers’ level of Harry Potter fandom was rated on a scale of one to five, based on a detailed questionnaire.