Referer, as it pertains to HTTP refer, is correct with a single “r”.
https://en.wikipedia.org/wiki/HTTP_referer
Also, “Roll”, as in “rollback” is written with a double “L”.
If you’d like support with the plugin, you can open a thread here (https://wordpress.org/support/plugin/block-referer-spam/) with your host details, logs, and/or excerpts of your .htaccess we’d be happy to help 🙂
Sorry, I’m not an English native. But if you write a plugin, you should know the declaration.
Thanks for Wiki-referral. If you read more as the heading, you will find your own answer.
“The HTTP referer (originally a misspelling of referrer) is an HTTP header field that identifies the address of the web page”
“The misspelling of referrer originated in the original proposal by computer scientist Phillip Hallam-Baker to incorporate the field into the HTTP specification”
“Referer Spam” = 14K google results
“Referrer Spam” = 84K google results
http://dict.leo.org/german-english/refer
http://dict.leo.org/german-english/referred
http://dict.leo.org/german-english/referring
http://dict.leo.org/german-english/referral
