1. 月亏：waning Gibbous 凸月(后半月) | waning 月亏 | Last Quarter 下弦月

2. 逐渐衰弱的：savior:救世主 | waning:逐渐衰弱的 | code:法规

3. 警告：流血 Bleeding | 警告 Waning | 拳手 Boxing

4. 渐亏的, 逐渐减弱或变小的：overhaul 检查 | waning 渐亏的, 逐渐减弱或变小的 | bypass 设旁路, 迂回

noun

1. a gradual decrease in magnitude or extent

e.g. the waning of his enthusiasm was obvious
the waxing and waning of the moon