Letup and Time-out

Letup noun - A usually gradual decrease in the pace or level of activity of something.

Time-out and letup are semantically related In some cases you can use "Time-out" instead a noun "Letup".

Time-out noun - A period of often involuntary inactivity or idleness.

Letup and time-out are semantically related in suspension of activity topic. Sometimes you can use "Letup" instead a noun phrase "Time-out".