pornographic adj.

1842, "ancient obscene painting, especially in temples of Bacchus," from French pornographie, from Greek pornographos "(one) depicting prostitutes," from graphein "to write" (see -graphy) + pornē "prostitute," originally "bought, purchased" (with an original notion, probably of "female slave sold for prostitution"), related to pernanai "to sell" (from PIE *perə-, variant of root *per- (5) "to traffic in, to sell").

A brothel in ancient Greek was a porneion. In reference to modern works by 1859 (originally French novels), later as a charge against native literature; the sense of "obscene pictures" in modern times is from 1906. Also sometimes used late 19c. for "description of prostitutes" as a matter of public hygiene.

Pornography, or obscene painting, which in the time of the Romans was practiced with the grossest license, prevailed especially at no particular period in Greece, but was apparently tolerated to a considerable extent at all times. Parrhasius, Aristides, Pausanias, Nicophanes, Chaerephanes, Arellius, and a few other [pornographoi] are mentioned as having made themselves notorious for this species of license. [Charles Anthon, "Dictionary of Greek and Roman Antiquities," New York, 1843]

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]

E. Bray in The Medical Archives [December 1872] proposed porniatria for "the lengthy and really meaningless expression 'social evil hospital' ...." In ancient contexts, often paired with rhypography, "genre painting of low, sordid, or unsuitable subjects."

Pornocracy (1860) is "the dominating influence of harlots," used specifically of the control of the government of Rome and the election to the Papacy during the first half of the 10th century by the noble but profligate Theodora and her daughters. Pornotopia (1966) was coined to describe the ideal erotic-world of pornographic movies. 

Middle English -ik, -ick, word-forming element making adjectives, "having to do with, having the nature of, being, made of, caused by, similar to," from French -ique and directly from Latin -icus or from cognate Greek -ikos "in the manner of; pertaining to." From PIE adjective suffix *-(i)ko, which also yielded Slavic -isku, adjectival suffix indicating origin, the source of the -sky (Russian -skii) in many surnames. In chemistry, indicating a higher valence than names in -ous (first in benzoic, 1791).

In Middle English and after often spelled -ick, -ike, -ique. Variant forms in -ick (critick, ethick) were common in early Modern English and survived in English dictionaries into early 19c. This spelling was supported by Johnson but opposed by Webster, who prevailed.

1952 (Norman Mailer), short for pornographic.