The phrase "additional stopover" means an extra place where a vehicle or person stops on their journey, beyond the planned stopping point. Full definition
Star Alliance — no stopover on one - way awards; complimentary stopover on; round - trips awards; up to (3) additional stopovers for $ 100 each (pointswithq.com)
Booking up to 3 additional stopovers at $ 100 each is tempting! (upgradedpoints.com)
Trips must be booked as roundtrips beginning and ending in the same city, though it's possible to build in additional stopovers along the way. (pointsaway.com)