pace up and down

Hello!
Is ‘to pace up and down’ an idiom?
Thank you for your time !

I would usually use ‘pace to and fro’ or ‘pace backwards and forwards’ (which are literal rather than idiomatic).
I would only use ‘pace up and down’ if I were speaking of a hill or a road, in which case I would say it wasn’t an idiom either.

I would use ‘pace up and down a room’ to suggest that you are anxiously waiting to receive important news. The classic example is of a man pacing up and down the room as he waits to hear news about the birth of his child.

Alan

Hello!
Thank you for helping me, Beeesneees and Alan!
I have in a coursebook a literary passage from the novel Rebecca by Daphne Du Maurier and I was looking for idioms for my degree paper trying to explain their function, why the author uses idioms, what the writer is trying to convey by using these devices, and the paragraph was: ’ After a while I got out and started to pace up and down, and found myself outside the building where the inquest was being held. A policeman appeared.’ So, ‘to pace up and down’ isn’t an idiom, maybe a phrasal verb?

It’s neither really. It’s just a simple verb used with an adverb phrase of place.