A person who has demonstrated they are part of a hive/collective "mind" or narrative, such as religious fanatics, highly partisan people, news site/talk show host fans, etc... Someone whose opinions can be known just by reading/listening to whatever they read or listen to regularly.
"She sounds like she's reciting republican party talking points, total hiver."
"He's a pure SJW hiver, if you've listened to him, you've listened to all of them."
"Like all hivers, his opinions on that come from others, he doesn't reason for himself."
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