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. 

Proto-Indo-European root meaning "to traffic in, to sell," an extended sense from root *per- (1) "forward, through" via the notion of "to hand over" or "distribute."

It forms all or part of: appraise; appreciate; depreciate; interpret; praise; precious; price; pornography.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit aprata "without recompense, gratuitously;" Greek porne "prostitute," originally "bought, purchased," pernanai "to sell;" Latin pretium "reward, prize, value, worth;" Lithuanian perku "I buy."

in Internet use (for example alt.right), it is from alt.* in the newsgroups naming system in Usenet. The term was introduced in 1987 and is said to be short for alternative, as it was meant to be outside the usual newsgroup administrative controls and thus include groups on controversial topics and pornography.

"to cut or pinch off the burned part of a candle wick," mid-15c., snoffen, from noun snoffe "burned part of a candle wick" (late 14c.), a word of unknown origin, perhaps related to snuff (v.2).

The meaning "to die" is from 1865; that of "to kill" is from 1932; snuff-film, pornography involving the actual killing of a woman, originally an urban legend, is from 1975.

also soft-core, 1966, in reference to pornography, from soft (adj.) + core (n.), and compare hardcore. 

"of pertaining to, or of the nature of pornography," 1853, from pornography + -ic.

1962, abbreviation of pornography.

1847, "one who writes of prostitutes or obscene subjects," from pornography + -er (1).

also hard-core; 1936 (n.); 1951 (adj.); from hard (adj.) + core (n.). Original use seems to be among economists and sociologists, in reference to unemployables. Extension to pornography is attested by 1966. Also the name of a surfacing material.