查询结果:

vt. 下降,衰落;倾斜,(成)斜面;拒绝,谢绝
vi. 下降,衰落;倾斜,(成)斜面;拒绝,谢绝
n. 下降,衰落;倾斜,斜面

拆分: de-下降 + -clin-倾,斜 + -e动词词尾 ⇒ 向下倾斜 

例:
a decline in productivity. 生产率下降。 
a decline in population. 人口下降。 
Profits declined by 6% this year. 今年收益减少了6%。 
The number of full-time staff has declined from 300 to just 50. 全职员工的数量从300人下降到了只有50人。