The full form of IANAL is I am not a lawyer
IANAL is the acronym for I am not a lawyer. It is typically stated by someone who is not a lawyer by trade but is giving their legal opinion on the law or in a legal matter.

Origin of IANAL
The abbreviation “ianal” became popular in the 1980s. It most likely came about as a widely used abbreviation after a popular cough syrup commercial aired on television where actors claimed: “I am not a doctor…” The phrase became popular on Usenet for non-lawyers and lawyers alike to post legal advice to people that requested it. However, if a person offering legal advice was a lawyer they changed the abbreviation to “ianyl” meaning I am not your lawyer. This disclaimer prevented the actual attorney providing the information from any legal ramifications. The abbreviation has been used widely since, mainly on the internet.

Other Meanings of “IANAL”
There are currently no other meanings to the internet chat abbreviation “ianal.”

Examples in Conversations
Friend 1: I need to stop downloading movies and songs from the Internet.
Friend 2: Why? I do it all the time.
Friend 1: I know, but I am pretty sure you can go to jail for doing it if you get caught.
Friend 2: IANAL, but I am just as sure they would go after the app you are using to do it, not you personally. It would take entirely too much time and money to go after every single person individually.
An internet chat between two co-workers regarding a recent incident.
Co-worker 1: I think you should talk to someone about the manager. His actions were uncalled for.
Co-worker 2: I know, but it’s his word against mine and we were alone in his office at the time. He will just say I came on to him instead.
Co-worker 1: Look, IANAL, but his behavior needs to go on record and the company needs to address the issue legally.