A person who was once someone's closest friend, but who became their worst enemy.
The pain received from having the worst enemy is worse, because of the painful loss of a friend.
Both parties usually become bitter and obsessive.
Josh: What? Why aren't you with Sara? You're always with her!
Jade: Oh, she's my Arch-Ex-Friend now. Haven't you seen her bitter attacks on Facebook?
by Reformed August 13, 2010

Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from daily@urbandictionary.com. We'll never spam you.

×