Steve Arons noted VN's mention of the "Newport Frill" in The Gift, though we have not yet heard how that item appears in the original Russian. I will be surprised if this is actually a literal translation, rather than something VN changed when he did the English version.
In any case, after looking through the list archives, I realized that there has never been a discussion here of the origin of the term. In Boyd's LoA notes to PF, he tells us that VN was referring to the "Newgate frill," a beard that traces the jaw line. It is named after Newgate prison, in London, because the beard resembles a noose hung round the neck of one about to be executed. In the context of Shade's fourth canto, we might then see this as a foreshadowing of Shade's death; or we might see it as a further show of Shade's feelings of guilt regarding Hazel's death. This latter interpretation would seem to fit with his notion (said in jest, of course) that the noose-like beard is "inveterate" in him; that noose (read: guilt) comes from something deeply rooted in his nature.
A separate question is why VN chose Newport instead of Newgate. The simplest explanation is that it was simply a mistake. He got the terms mixed up in his mind. Yet knowing how precise VN was, in his memory and his writing, we might be tempted to find some method in the change of terms. If VN did substitute Newport intentionally, the most obvious reference would be to Newport, Rhode Island--the well-known seaport on the south coast of that tiny New England state. Newport is a resort town, known for its mansions and jazz and folk festivals. I wondered once if a lot of folkies or jazz musicians wore this kind of beard, but I see no evidence of that, and the Newport Folk festival only originated in 1959. (The German composer Richard Wagner, however, sported a grand example--see his wikipedia page). Another possibility I have kicked around is that VN was subtly referring to Ansel Bourne (see the archives), the Rhode Islander (he lived about 30 miles from Newport) who suffere
d from strange fits and had a famous dissociative episode at the age of 61. (Robert Ludlum, by the way, named his Bourne character after Ansel Bourne.) Bourne, in the only photo I've ever seen of him, wore his beard in a style that closely resembles the Newgate Fringe, completely off the cheeks but creeping up onto the lower half of his chin a bit. If this were VN's intended reference, then Ansel Bourne's condition would be the thing deeply rooted within John Shade.
But again, none of this could be true if VN actually used the term Newport Frill in the original Russian of The Gift. So that would be good to know.