Death knell and Point of no return

Death knell noun - A bell rung to announce a death.

Point of no return and death knell are semantically related. In some cases you can use "Point of no return" instead a noun phrase "Death knell".

Point of no return noun - A line that when crossed permits of no return and typically results in irrevocable commitment.

Death knell and point of no return are semantically related. Sometimes you can use "Death knell" instead a noun phrase "Point of no return".