#take a shot everytime i said the word “dehumanizing”

[onlysevvs]

If you're ok with calling Severus "Snivellous" then you should be ok calling Luna "Loony".

Both nicknames were used to mock and dehumanize the person they were bullying.

Snivellous = Snivelling, the action of crying in a feeble, or fretful, way.

Loony = it's in the name, LOONY, an adjective to describe someone who is mad or crazy. (— or even silly, but in the context of Luna, it is not being used in that way.)

"Snivellous" and "Loony" were both used by bullies and tormentors to dehumanize both Severus and Luna, because both of them were seen as "odd", "crazy", or "strange".

If you're okay with using the dehumanizing nickname Severus had, you should have no issue using Luna's dehumanizing nickname too.