in, to sell," cf. L. pretium "price") + graphein "to write." Originally used of classical art and writing; application to modern examples began 1880s. Main modern meaning "salacious writing or pictures" represents a slight shift from the etymology, though classical depictions of prostitution usually had this quality.
"I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description [hard-core pornography]; and perhaps I could never succeed in intelligibly doing so. But I know it when I see it, and the motion picture involved in this case is not that." [U.S. Supreme Court Justice Potter Stewart, concurring opinion, "Jacobellis v. Ohio," 1964]
Pornographer is earliest form of the word, attested from 1850. Pornocracy (1860) is "the dominating influence of harlots," used specifically of the government of Rome during the first half of the 10th century by Theodora and her daughters.