Standard language includes both spoken and written varieties. However, linguistic planning has traditionally focused more on the written form, with some linguists even questioning the existence of a standardized spoken language. Today, the need for rapid communication, access to digital technologies, cultural and social changes, and individuals’ desire for self-expression have shifted attention towards spoken language. The rise of social networks and modern technologies has integrated spoken language into written formats, such as text messages, online communications, and narratives. As a result, colloquial and informal forms have become prominent in the Persian cyberspace and story dialogues. Although various studies have investigated this type of writing, there has been little focus on its impact on dictionaries. This study analyzes the influence of colloquialism in Persian slang dictionaries and how it manifests across different linguistic levels—phonological, lexical, syntactic, and semantic. It also examines the differences between general and slang dictionaries. The findings indicate that colloquialism is present at all linguistic levels, particularly in the inclusion of colloquial and informal words in Persian slang dictionary entries. However, this trend is not consistently applied across different dictionaries, and there are discrepancies in how spoken elements are represented. A deeper understanding of spoken language can enhance our knowledge of its role in the evolution of Persian. Additionally, developing reliable resources on spoken language for translators, editors, and literary writers can improve linguistic quality and foster more effective interactions between writers and their audiences.