How did "re" + "join" semantically compound to mean "riposte"?
In French, « joindre » means "to join". What semantic notions underlie « joindre » with the 2020 English "rejoin", which means to riposte? How did rejoindre shift to signify the 2020 English "rejoin"? Clearly, "to rejoin" and "to riposte" don't mean the same actions!
This French Stack Exchange comment vouches that Etymonline below is wrong, because rejoindre has never meant "to answer a legal charge".
"to answer," mid-15c., legal term,
from Middle French rejoin-, stem of rejoindre "to answer to a legal charge,"
from Old French re- "back" (see re-) + joindre "to join, connect, unite,"
from Latin iungere "to join together, unite, yoke," from nasalized form of PIE root *yeug- "to join." General (non-legal) meaning first recorded 1630s.
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.