death knell(redirected from a death knell)
A signal of the impending end or ruin of something, especially a business, organization, or activity. Refers to the sound of a bell ringing (the knell) from a church to indicate that someone has died. The geometric expansion of the Internet and digital media has tolled the death knell for countless print-based businesses around the world.
Something that indicates impending failure, as in His low scores sounded the death knell for his ambitions. The noun knell, used for the ringing of a bell since at least a.d. 1000, is rarely heard today except in this figurative phrase.