A "free stopover" means that during a trip, you can make a temporary break at a location besides your final destination without any extra charge. Full definition
You wrote: «Most frequent flyer programs don't allow free stopovers on awards, let alone on one - way award tickets.» (onemileatatime.boardingarea.com)
The airline's policy of allowing free stopovers in Japan can increase the value of your ticket since you can visit Japan and another destination in Asia on the same award flight. (rewardexpert.com)
Most frequent flyer programs don't allow free stopovers on awards, let alone on one - way award tickets. (onemileatatime.boardingarea.com)