'death knell' definitions:

Definition of 'death knell'

From: WordNet
noun
An omen of death or destruction
noun
A bell rung to announce a death [syn: death knell, death bell]

Definition of 'death knell'

From: GCIDE
  • Knell \Knell\, n. [OE. knel, cnul, AS. cnyll, fr. cnyllan to sound a bell; cf. D. & G. knallen to clap, crack, G. & Sw. knall a clap, crack, loud sound, Dan. knalde to clap, crack. Cf. Knoll, n. & v.] The stroke of a bell tolled at a funeral or at the death of a person; a death signal; a passing bell; hence, (figuratively), a warning or harbinger of, or a sound indicating, the passing away of anything; -- also called death knell. [1913 Webster +PJC]
  • The dead man's knell Is there scarce asked for who. --Shak. [1913 Webster]
  • The curfew tolls the knell of parting day. --Gray. [1913 Webster]

Definition of 'death knell'

From: GCIDE
  • death knell \death" knell`\, n.
  • 1. A stroke or tolling of a bell, announcing a death; a knell[1]. [1913 Webster]
  • 2. Hence: (figuratively) A sign or harbinger of the end, death, or passing away of anything. [PJC]