What does stage fright mean? Is it an idiom?

[DeyaT]

ESL/EFL Test "Stages", question 6

It's quite normal when you make your first speech in public to suffer from stage ..........

(a) fear
(b) nerves
(c) fright
(d) anxiety

ESL/EFL Test "Stages", answer 6

It's quite normal when you make your first speech in public to suffer from stage fright.

Correct answer: (c) fright
_________________________

Hi,
Is stage fright the same as stage fever?

Deya

[Alan]

Hi,

This means frightened to go on the stage.

Alan
_________________
English as a Second Language
You can read my ESL story Present Simple

[Ceo Neeraj]

Hi,

Why fear can't be the option for the question above? I think it also suits the sentence.
Help.

[Torsten]

Fear is not correct because 'stage fright' is an idiom while 'stage fear' is not. So the key to your question is the word 'idiom'. Do you know what an idiom is?
Regards,
Torsten

TOEFL listening lectures: A university science lecture on Island Biogeography

[Ceo Neeraj]

Dear Torsten,

I think that the idioms are the group of words, which if used together as a group; sound logical and meaningful, but not if taken individually into account.
Please correct me if i am wrong.