I'm too lazy to remember which story to pick the quote out, but one of my favorite Vlad moments from Steven Brust is when Our Hero is having some sort of discussion with Aliera e'Kieron—is it Yendi? as I'm pretty sure she was still Heir—and the line goes something like, "Blah blah blah," Aliera hissed. Yes, I'm aware there are no sibilants in that sentence, but she still hissed it. One of those quiet barbs at an unknown writer, we would guess. Or else a golf-slap to Terri Windling, his editor, who might actually have scrawled on the draft, "There are no sibilants in that sentence". Well, okay, no, she wouldn't have. She just would have written, "Sibilants?!" At any rate, as we have sibilants for S, what is our word for the F sound? I was chuckling at the old Vlad moment while thinking about a bit of dialogue that required a proper, "Ffffffffuck!" and for some odd reason, the question occurred to me. Can't imagine why. It's also silly to me that I don't already know this word. What the ffffff― ... ... er, right.
Now I'm Having Way Too Much Fun I found strident, as a result of your suggestion, and fricative is not a word I would have found easily since I didn't think to search "sound of the letter F", but it also turns out that sibilants are a subset of fricatives. Damn. Wikipedia is occasionally good for something. Still, though, I'm not sure the point would come across. The "stridence of his 'fuck'" is a hard (ha!) concept to work with. But it's true, there is a lost art of the F. It's a sound that reveals so much about the perspective of whatever comes next. Better, then, the "stridence of his strident". It would certainly work, but the same article tells me that spirant (to fricative) and strident (to non-sibilant fricatives) are unstandardized terms. Is there, then, a standardized term for the F subset of fricatives? But I thank you. For all I devote to the conveyance of ideas through written word, it's also true that I loathed grammar lessons, still to this day disdain vocabulary lessons (especially since I never once saw the word "lexicon" in my vocab study lists), and could not perform a proper syntactic diagram to save my life. Every once in a while, this results in the need to ask a silly question. Oh, fffff—.... No, seriously, I am not going with the nuance of his labiodentistry. Then again, a chapter spent in labiodental frolic might well be one of those opportunities that doesn't knock twice. Come on, is there nothing more specific than fricative while less rhythmically problematic than voiceless labiodental fricative? How about labiofricking? Nope.
Specifically: a voiceless labiodental fricative. V is a voiced labiodental fricative--in English. In Spanish it's bilabial. Germany, Austria and Switzerland have several different regional accents, so it is pronounced both ways there--and of course spelled W, not V. S, SH, Z and ZH are palatal fricatives; the first two voiceless, the others voiced. Along with the affricates, J and CH, these are the sibilants.
