meaning of "least of all".

English as a Second Language English Vocabulary, Grammar and Idioms
1

Good Evening sir,

Please tell me the meaning and proper use of “least of all”,I do not know if it is an idiom? Please tell me the difference “she did not mind in the least”
He neither needs certificates from anyone,least of all techers."

Thanks a lot.
sonia*

2

Least of all = especially not. It is in the DICTIONARY.

In the least = at all. It is in the DICTIONARY, too.

3

thanks a million sir…