mid-15c., from Middle French noun use of rejoindre "to answer to a legal charge" (see rejoin (v.2)). Originally "defendant's answer to the replication" (the fourth stage in the pleadings in an action at common law). For noun use of infinitive in French law terms, see waiver.
it brought a sharp rejoinder from the teacher
reject
rejection
rejoice
rejoicing
rejoin
rejoinder
rejuvenate
rejuvenation
rejuvenescence
rejuvenescent
rekindle