(R)eply (E)veryone (tard)
Someone who has not mastered the very simple difference between email's "reply" and "reply all" actions. The RE-tard is consistently spamming a distribution list's mailbox with their comment, which is relevant only to them and the sender. A true RE-tard will do this even when the original sender of an email to many people list explicitly requests recipients do not "reply all."
I can't stand it when a new system rolls out at my job. My AVP boss always spams her stupid questions to the whole company like the RE-tard she is.