Last gasp and Zero hour

Last gasp noun - The point of death or exhaustion or completion.

Zero hour and last gasp are semantically related. In some cases you can use "Zero hour" instead a noun phrase "Last gasp".

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

Last gasp and zero hour are semantically related. Sometimes you can use "Last gasp" instead a noun phrase "Zero hour".