Clipping of pornographic or pornography. Attested from mid-20th century.
Meanings
(informal, not-comparable) Pornographic.
That's a porno film.
[…]ultra-risqué pictures verging on the pornographic (the most porno of the last-named have not yet made it to the TV screen, but they are getting there fast—witness the storm of protests over the situation comedy “Soap”). 1978, Mario Pei, Weasel Words: The Art of Saying what You Don't Mean, page 15:
For reasons that still baffle me, “Deep Throat” became the one porno film in New York chic to see and to seen at, even before the court case, even before Earl Wilson wrote about it. 1973 January 21, Vincent Canby, “What Are We To Think of ‘Deep Throat’?”, in The New York Times, →ISSN: