👉 The Fluid rule is a linguistic principle that governs the substitution of one noun phrase for another within a sentence, ensuring that the substitution doesn't alter the sentence's meaning or introduce ambiguity. It allows for the replacement of a noun phrase with another that is semantically similar, maintaining the original sentence's clarity and coherence. For example, in the sentence "I saw a dog and a cat," one might replace "dog" with "feline" without changing the intended meaning, provided "feline" is understood to refer to a cat. This rule helps in creating varied and natural-sounding sentences while preserving the original message.
