The state of being slow,usually noticing things everyone else knows already or being the last one to get a joke.Not exactly retardation,just slow thinking.
John started laughing out of nowhere,i asked him what was wrong and he said i finally got that family guy joke from last year,total mental re-tardy.
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.