What is the definition of Phrases Fluid?

"A phrase is said to be 'fluid' when it dances effortlessly from one meaning to another, like a magician's sleight of hand with words. It's as if it's trying to outwit the laws of grammar and logic while still making coherent sense. But here's a bit of an unsettling example: 'The 'fluid' explanation for my procrastination is that I'm just trying to make the 'fluid' transition from avoiding work to actually doing it.'"