Meaning of the word "not turn a hair" in English

What does "not turn a hair" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

not turn a hair

US /nɑt tɜrn ə hɛr/
UK /nɒt tɜːn ə hɛə/
"not turn a hair" picture

Idiom

to show no sign of fear, surprise, or emotion in a difficult or alarming situation

Example:
Even when the car skidded, she did not turn a hair.
He heard the bad news but did not turn a hair.