Definition of no (or not) room to swing a cat in US English:

no (or not) room to swing a cat

phrase

humorous
  • Used in reference to a very confined space.

    • ‘You don't need to have been inside a dog trap yourself to understand that there isn't room to swing a cat in there,’
    • ‘We have a splendid cabin and there's plenty of room - but in most places there isn't room to swing a cat.’