Does the literal meaning make no sense? Then it's an idiom. Have you ever seen anyone really have a blue face? Nope.
surprise, idea, shock
Unless "the blue" is followed by a noun (e.g. the blue sky), blue is a noun, and the is an article.(e.g. the idiom into the blue, meaning parts unknown, literally the sky).
It means easily angered, or not in control of your emotions.
"To be" is not an idiom - it's a verb.
"Blue blood" LITERALLY means blood that is blue in color.
it means a highly valued asset.
It means he's really angry.
Does the literal meaning make no sense? Then it's an idiom. Have you ever seen anyone really have a blue face? Nope.
surprise, idea, shock
It means the favorite or favored person in the group. A similar idiom is "fair haired child."
It means being ticked off, or very mad.
'Out of the blue' is a terse form of the expression 'out of a clear blue sky' (to mean 'unexpectedly, without foreshadowing'). It is not really a figure of speech, but an idiom. ('idiom':: an established expression in a language where the meaning is not necessarily what one would anticipate from the given meaning of the individual words).
Unless "the blue" is followed by a noun (e.g. the blue sky), blue is a noun, and the is an article.(e.g. the idiom into the blue, meaning parts unknown, literally the sky).
It means easily angered, or not in control of your emotions.
Needless to say the sky is blue! This is an idiom. Meaning that it is given or obvious.
"To be" is not an idiom - it's a verb.