1. (of the moon) more than half but not fully illuminated; between half-moon and full moon.
Usage: astronomy; most common sense
2. Humped or swollen; having a rounded, bulging shape.
Usage: formal; less common

Examples

• The gibbous moon was bright enough to read by.
• We watched the moon transition from crescent to gibbous over several nights.
• A gibbous moon occurs when more than half of the moon's surface is illuminated.
• The old man had a gibbous back from years of stooping.
• The gibbous shape of the shell made it difficult to stack.