SPRAINTS AND FORNICATION.

I've been reading The London Train (P.S.) (a birthday gift from jamessal), and I was sent to the dictionary by the following sentence: "She showed them a dusty depression on the bank that might be where the otters slept by day, and their spraints nearby, blackish messes of fish scales and fragments of bone, probably eel bones." Spraints, it turns out, are (to quote the OED) the excrement of the otter. It's from Old French espraintes, from espraindre 'to squeeze out' < Latin exprimere: an expressive word.

And now a quiz. A correspondent writes that he canvassed his friends about the word "fornication" and discovered that most of them understand it as referring to any sex at all, whereas the dictionaries define it only as sex outside of marriage (which is the way I understand it): "This makes me think there's been an interesting shift in the meaning of the word, perhaps only during the twentieth century (the OED's entry is unchanged since 1e, in 1897). Do you or your readers know whether this shift has been studied?" I don't; do you?