Definition from Wiktionary, the free dictionary
rejoinder (plural rejoinders)
- (law) defendant's answer to the replication.
- A quick response that involves disagreement or is witty; especially an answer to a reply.
- (patents) in US patent law re-insertion, typically after allowance of a patent application, of patent claims that had been withdrawn from examination under a restriction requirement.
Formally, a reply to a reply, but in non-legal sense also used for simple replies.