What's the meaning of OUT OF BLUE here ?
When I saw the phrase , I thought it was used to describe something related to emotion.
but when I google it , it shows : suddenly .

“Well, this is out of the blue.” how do I know the meaning is "suddenly" or "depressed"

Does it have other meanings?

Question

What's the meaning of OUT OF BLUE here ?
When I saw the phrase , I thought it was used to describe something related to emotion.
but when I google it , it shows : suddenly .

“Well, this is out of the blue.” how do I know the meaning is "suddenly" or "depressed"

Does it have other meanings?

Answer

You can remember them with the reason or origin of the phrases.

- "blue" as melancholic or depressed:  The color feels cool.  It is the impression people get from the color.

- "out of the blue":  Think of it as "a thunderbolt out of the blue sky", which is something totally unexpected.  Hence the meaning "unexpected" or "suddenly".

Answer

OUT OF THE BLUE: suddenly, seeming to come from nowhere.

Examples: 
 
- The idea came to me from out of the blue.
- Out of the blue, a car approached.

BLUE: a sad mood or feeling

Examples:

- I'm staying at home today since I'm feeling a bit blue. 
- Rainy days always give me the blues.
- https://www.youtube.com/watch?v=SbJpzYHEnPI

Answer

I am feeling blue/ she seems a bit blue lately - depressed

Out of the blue - Suddenly. This phrase can not be said any other way. You will always see it in its full form as you do here.

لا تفوّت فرصة تعلّم لغة جديدة وأنت مرتاح في منزلك. تصفّح مجموعتنا المختارة من مدرّسي اللغات ذوي الخبرة وسجّل في درسك الأول الآن!