Smut is a word often a word used by the younger generation of Millennials and GenZ. The word 'smut' is often used to describe sex or erotic materials (aka 18+ shit.) contained in fanfiction or books. This can also apply to art too but is usually the former.
Smut can be all kinds of sexual activity. This includes fetishes, omegaverse, and just straight
porn. Smut is also commonly referred to as
Lemon, or Lime. Though the definition of
Lemon is very similar to Smut, Lime is referred to when sexual stuff is mentioned but
now outright written in a story.
Td;Lr: smut is basically just
porn usually in fanfiction form.
Person 1: Do you know the fanfiction "Todoroki and the
Special Night"? Its my favorite!
Person 2: Isn't that the one with the Smut...? You
kinky bitch.
Person 3: What is smut?
Person 2: Smut is sexually explicit content in a fanfiction or book.
Person 3: Wow, Person 1 sure is
kinky!"
Person 1: Hey!