Here you go:

A "surreply" is a supplemental reply to a response to a motion. "Sur" translates as on or over in the sense of supplemental. Taking filings in the order they happen, a party files a motion, the other side files a response (sometimes called an "opposition"), then the party that filed the motion replies. With a surreply, the party that originally filed the motion files a supplemental, second reply. In Federal court, surreplies generally are prohibited by local court rules without the court's permission. Permission is most commonly sought to file a surreply when events happening after the filing of the reply brief make a further brief desirable. For example, when lots of motions are flying, it's not uncommon for one party to insert an argument, often in a footnote, in one of the briefs involving a motion it doesn't really relate to. Filing a surreply (or surresponse for the party opposing the original motion) in such a circumstance allows the party opposing that argument to make sure its counter-argument is considered when the court is deciding the appropriate motion.

Coyote