Why do dictionaries wait for widespread and sustained use before adding slang words?

Dictionaries wait for widespread and sustained use before adding slang words because they function as descriptive tools that document how language is actually used, rather than as prescriptive authorities that dictate how it should be used.123

Lexicographers collect citations to track vocabulary, but they must distinguish between enduring language and "trendy flashes in the pan" that quickly disappear. Because slang can be short-lived—often failing to capture the public imagination for long—editors look for three specific criteria to ensure a word has become a meaningful part of the language:12

• Frequent use: The word must be used consistently over time.2
• Widespread use: The word should be used across different regions or industries, making it likely that an average adult will encounter it and need to understand its meaning.2
• Meaningful use: The word must have a clear, agreed-upon definition.2

By requiring this evidence, lexicographers ensure the dictionary remains an accurate "user’s manual for communication" rather than a record of fleeting terms that may soon vanish from common usage.12