Point of no return and Zero hour

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

Zero hour and point of no return are semantically related. In some cases you can use "Zero hour" instead a noun phrase "Point of no return".

Zero hour noun - A time or state of affairs requiring prompt or decisive action.

Point of no return and zero hour are semantically related. You can use "Point of no return" instead a noun phrase "Zero hour".