While it might seem like an interjection due to its use in expressing amusement, it's not technically classified as one because it lacks the traditional characteristics of an interjection:
* Independent expression: Interjections are typically stand-alone words or phrases, expressing a sudden emotion or reaction. "lul" often appears in conjunction with other text, sometimes as a reaction to something humorous.
* Grammatical separation: Interjections are usually separated from the rest of the sentence by a comma or exclamation mark. "lul" is often integrated into the text flow, lacking this separation.
Ultimately, "lul" is a slang term, not a formal grammatical element. Its meaning and usage rely on the context of online communication.