Well the Greek roots are literally "writing about prostitutes". I'd argue explicit depiction of sex for the sake of getting off is porn. In literature, drawing, photo, or video. There's even the audio form.

English also has "erotica". Which is... porn which has some non-porn value? Semi-clothed porn? Most romance fiction is more to the clothed than unclothed end of the erotica spectrum, anyway. I wouldn't class most as porn. Though there sure are some pornographic books. I was surprised to learn how many synonyms for the genitalia there are.