What is the meaning of Knell?

To ring a bell slowly, especially for a funeral; to toll.

To signal or proclaim something (especially a death) by ringing a bell.

To summon by, or as if by, ringing a bell.

The sound of a bell knelling; a toll (particularly one signalling a death).

A sign of the end or demise of something or someone.

Source: wiktionary.org