Periphrasis is a rhetorical device that involves using excessive and longer phrases to express an idea that could be conveyed with fewer words or in more direct terms.

It's often used to be polite, to add emphasis, or to create a poetic effect.

Instead of saying ‘I'm busy,' one might use periphrasis to say, ‘At the moment, it might be quite challenging for me to allocate time for additional tasks.'

This approach can make the language more formal or deferential. And it can add a note of humor.

When you have no room for another helping of potatoes, instead of saying “I'm full,” you could say “Alas, I've attained corporeal satiety.”

Periphrasis can be used to adjust the tone, making your communication more sophisticated, intentionally indirect, or funny.

It's particularly useful in diplomatic language or in contexts where politeness and formality are required.