Could Nearly Headless Nick actually lose his head?

Question

I looked around and couldn't find a duplicate for this question.

I don't have the books on me, but I remember Nearly Headless Nick mentioning that he was not allowed to hang out with the actually headless ghosts, because he was, well, nearly headless. His head was still attached by some "skin". My question is, given his inability to interact with normal matter, is it ever possible for him to become completely headless? Is there a spell, or something else, that could potentially remove his head? Or are ghosts permanently stuck in the physicality they had when they became ghosts?

And as a follow-up question, what would happen to his head? Would it simply disappear, or would it become some kind of ghostly waste? Would it simply hang around wherever Nick left it, or would it be the true ghost and his body go to waste?

Looking for as many canonical sources as you can find!

Answer 1

Highly Unlikely.

We have this quote from Pottermore - Ghosts:

No physical pleasure remains to them

This most likely refers to the fact that their body can feel no pleasure, even through interaction with themselves. This fact I feel is evidenced in the Deathday Party scene.

(...) the Fat Friar, a cheerful Hufflepuff ghost, who was talking to a knight with an arrow sticking out of his forehead.

Harry Potter and the Chamber of Secrets

Now from this two things can be garnered, weapons left stuck into the body when dying also become part of the ghost and this ghost did not remove the arrow.

You may ask if he could remove the arrow, why would he want to? I also pose that IF he could remove the arrow, Nick could use it to slice the single strain of sinew keeping his head attached.

Considering it's been 500 years since his death it is likely as @Richard said that he explored all the options available to him.

Like @Randal'thor I shall also mention @DVK's answer here but for different purposes. In it we see that he mentions Headless Hockey and Headless Polo, presumably this is Hockey and Polo using heads instead of balls. From this we can take that ghosts can receive no further damage otherwise each member of the Headless Hunt would be the owner of a severely battered and mostly destroyed head.

TL:DR Very unlikely ghosts can take any further physical^† damage to their bodies.

^{†: Nick does get petrified but I would not consider this physical damage.}

Answer 2

Probably not.

Ghosts do not have a physical body: they are merely spiritual shades of what used to be people. Their corpse can be treated in the same way as any other, and the physical bodies of most of the ghosts we encounter in the series must have decayed long ago. So it seems that the visible form taken by a ghost is what their body looked like at the moment of death: hence Nearly Headless Nick looks as he did just after he was executed, not the mouldering skeleton he physically became afterwards. For the same reason, ghosts retain the clothes they were wearing when they died: hence Nearly Headless Nick never changed out of his Elizabethan ruff into something more appropriate to this day and age.

Given this assumption, it's clear that his ghostly appearance can never change: he'll always be nearly headless.

This doesn't contradict DVK's answer here, since the games he mentions involve ghostly interaction but not any change in the 'bodies' of the ghosts involved, since their heads are already detached.

As Richard pointed out in a comment, it also stands to reason that Nearly Headless Nick would have got himself properly beheaded if he could. He spent several hundred years hanging out in a whole building full of witches and wizards, including some of the greatest of their age such as Dumbledore. If they couldn't tell him how to get his head entirely removed, nobody could; and if they could, he would presumably have done it, since nearly headlessness is his main grievance in life death.

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As for your bonus question (which admittedly is now hypothetical only), consider the completely headless ghosts, such as those involved in the Headless Hunt. They get on perfectly well in life death with their heads detached from their bodies, and neither head nor body goes to waste; both remain part of the ghost, able to move and communicate.