The phrase "complimentary roundtrip" means that something, like a ride or a ticket, is given to someone for free to their destination and back without having to pay anything. Full definition
Private balconies have comfortable seating and boast gorgeous views of the Camelback Mountains, and the Extreme WOW Suite comes with complimentary roundtrip airport transfers and WHEELS valet parking. (vacationidea.com)
Stays that are a minimum of seven nights receive an additional $ 100 Amber Spa credit per person, per stay and complimentary roundtrip coach transfer service from the airport to the resort. (travelagentcentral.com)
Plus, Lindblad is providing complimentary roundtrip charter flights from Ecuador to Galápagos for guests that book Wild Galápagos Escape or Wild Galápagos & Peru Escape on the above noted departures. (travelagentcentral.com)