Gibbous moon (def): The Moon as it is seen a few days either side of a full moon, i.e., when the full moon is waxing or waning and the illuminated part is less than a full circle.
Gibbous moon (def): The Moon as it is seen a few days either side of a full moon, i.e., when the full moon is waxing or waning and the illuminated part is less than a full circle.