Jam and Zero hour

Jam noun - A crowded mass (as of cars) that impedes or blocks movement.

Zero hour and jam are semantically related. In some cases you can use "Zero hour" instead a noun "Jam".

Nearby Word: jamming

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

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