falling-off
noun🔊/ˌfɔːlɪŋ ˈɒf/
🔊/ˌfɔːlɪŋ ˈɔːf/
(British English) (also fall-off British and North American English)
[singular]- falling-off (in something)
a reduction in the number, amount or quality of something （数量的）减少；（质量的）降低