"Blue blood" LITERALLY means blood that is blue in color.
Literally it means that you have a heart, you physically possess that bodily organ.
The idiom your blood is boiling usually means that you are mad/furious.
An idiom is something that does not mean what the phrase says literally, so yes. You can't actually laugh your head off.
Feeling blue means you are sad or possibly depressed.
Feeling blue means you are sad or possibly depressed.
This is not an idiom. They mean that someone literally has a tapeworm inside their intestines. It's a parasitic organism.
It means someone has blue eyes.
get scared or terrified
It means swearing violently and creatively.
An idiom usually is a sentence, or part of one. It certainly can be used as part of a sentence. The way to tell if it's an idiom is if it makes sense the way it's literally written.
if someone is true-blue, they support something or someone completely n…
Nothing. I think you may mean "mend fences," which literally means to repair or fix the broken spots in a fence. Used as an idiom, it would mean to fix or repair a "broken" relationship by apologizing, compromising, and communicating.