Just a phrase, providing what it describes matches one of the literal definitions of trauma, and is caused by something matching one of the literal definitions of termination.
Yes
Can you figure out the meaning by defining the terms? Yes, so it's a phrase instead of an idiom.
The phrase "laid eyes on" is an idiom.
An idiom is a phrase that doesn't make any sense unless you know the idiomatic definition. This phrase means exactly what it looks like, so it's not an idiom.
An idiom is a phrase that doesn't make any sense unless you know the definition. This phrase makes perfect sense, so it is not an idiom. The room became quiet.
Stuck in a rut is a phrase, but I am not sure if an idiom is the same thing as a phrase. You may be thinking of a cliche and "stuck in a RUT" is a cliche. "Stuck in a road" is neither cliche nor idiom.
A phrase unique to a particular language is called an "idiom." Idioms often have meanings that cannot be derived from the individual words used in the phrase.
idiom
yes
Yes it is.
to do nothing nothing to do
You cannot understand an idiom without knowing ahead of time what it means. A phrase is just part of a normal sentence.