zodiacism
Birthday prejudice. The belief that all members of a particular range of birthdays possess characteristics or abilities specific to that range of birthdays, especially so as to distinguish them as romantically compatible or incompatible with members of a different range of birthdays.
Example:
Jade: Girl, be careful with him, he's a Taurus. You know how THEY are!
Cinnamon: Jade, that's zodiacism! Don't judge my future ex-husband based on his damn birthday!
Jade: Girl, be careful with him, he's a Taurus. You know how THEY are!
Cinnamon: Jade, that's zodiacism! Don't judge my future ex-husband based on his damn birthday!