5. a common expression whose meaning cannot be guessed from individual words eg 'I'm feeling under the weather
An idiom is a phrase that has a figurative meaning different from its literal meaning, while an idiomatic expression is a specific phrase or sentence structure that is characteristic of a particular language or dialect. Idioms are a type of idiomatic expression, but not all idiomatic expressions are idioms.
"Turn a deaf ear" is an idiomatic expression meaning to ignore or pay no attention to something.
You can, but it is not idiomatic English. If you mean that people worked straight through their lunch time, use No one took lunch
"As deaf as a post" is an idiomatic phrase that means 'very or extremely deaf'.
"Grow homesick" is an idiomatic expression that means to start feeling longing or nostalgia for one's home or a familiar place. It implies a deep emotional connection to one's roots and a desire to return to a place that feels like home.
babysitting
This mean someone is pretending to have good intentions, but in fact, it's just the opposite.
traitor, backbiter
to be un happy
Think about this and you can figure it out. An idiom seems to mean one thing but actually means another. Does "with regard" mean just what it seems to? Yes, it does. Therefore, this phrase is not an idiomatic expression.
It means that it is extremely easy.
This is slang - it means your spouse.
A distinct style or character.
It can mean that something is difficult or that a person is stubborn.
Force someone to do something
it is just an insult
Its not idiomatic Latin, but it could be translated "well enough"