poetic/literary <诗/文>
in sing.
1- the sound of a bell, especially when rung solemnly for a death or funeral钟声; （尤指）丧钟声。
1.1
- figurative used with reference to an announcement, event, or sound that is regarded as a solemn warning of the end of something〈喻〉事物行将结束的信号：
the decision will probably toll the knell for the facility.
该决定可能会为这项设施敲响丧钟。
no obj.
1- (of a bell) ring solemnly, especially for a death or funeral（铃, 尤指丧钟）敲响。
1.1
- with obj. proclaim (something) by or as if by a knell似发出丧钟般地宣告（某事）。
词源
Old English cnyll (noun), cnyllan (verb), of West Germanic origin; related to Dutch knal (noun), knallen (verb) 'bang, pop, crack'. The current spelling （dating from the 16th cent.） is perhaps influenced by BELL1.