1) Acknowledgement of death 
A death knell is the ringing of a bell to announce a death. This is also called tolling the bell. The ancient custom of ringing a church bell at the actual time of death (the Passing-Bell, or rather the Death Knell) fell into disuse in England by the end of the 18th century. More customary at the end of the 19th century was to ring the Death Knell...
[n] - an omen of death or destruction 2. [n] - a bell rung to announce a death
death bell noun a bell rung to announce a death
a harbinger of the end, death, or destruction of something. · See