Here's why:
* Slang is informal: Slang is by definition casual and informal language. It often originates from specific groups or communities and is not considered appropriate for formal settings.
* Formal English aims for clarity and precision: Formal English focuses on using precise and established vocabulary, often with Latin or Greek roots.
* Alternatives in formal English: Instead of "slang," formal English might use terms like:
* colloquialisms: This refers to everyday informal language, but it is more neutral than "slang."
* vernacular: This term denotes the language spoken by a particular group of people.
* idiomatic expressions: This refers to phrases with a figurative meaning that is different from the literal meaning of the words.
Example:
* Informal: "She's totally rocking that outfit!"
* Formal: "She is wearing an extremely fashionable outfit."
* Formal with explanation: "She is wearing an outfit that is considered very stylish within the current fashion trends."
While formal English avoids using "slang," it might acknowledge the existence of slang in academic settings or discussions about language.