Nail Biting – Nail biting, also known as onychophagy or onychophagia (or even erroneously onchophagia), is an oral compulsive habit. It is sometimes described as a parafunctional activity, the common use of the mouth for an activity other than speaking, eating, or drinking.

Nail biting – Wikipedia

https://en.wikipedia.org/wiki/Nail_biting

Nail biting, also known as onychophagy or onychophagia (or even erroneously onchophagia), is an oral compulsive habit. It is sometimes described as a parafunctional activity, the common use of the mouth for an activity other than speaking, eating, or drinking.