tail off

Từ điển Việt Anh Việt 4in1 - English Vietnamese 4 in 1 Dictionary

tail off (also tail away British English) phrasal verb (see also ↑tail)
1. to become gradually less, smaller etc, and often stop or disappear completely:
Profits tailed off towards the end of the year.
2. written if someone’s voice tails off, it becomes quieter and then stops:
‘I didn’t mean ...’ Her voice tailed off in embarrassment.