Here's why:
* Definition of a phrase: A phrase is a group of words that functions as a single unit of meaning. It doesn't have to be a complete sentence.
* Single-word phrases: A single word can function as a complete thought or expression, fulfilling the role of a phrase.
Examples:
* "Help!" This is a single word that conveys a strong emotion and request.
* "Stop!" This single word is an imperative command.
* "Wow!" This single word expresses surprise or amazement.
These single words function as phrases because they convey complete meaning on their own, even though they lack the structure of a traditional multi-word phrase.