<unk> , also known as onychophagy or onychophagia (or even erroneously onyhophagia), is an oral compulsive habit of<unk>  one's fingernails. It is sometimes described as a parafunctional activity, the common use of the mouth for an activity other than speaking, eating, or drinking.<unk>  is very common, especially amongst children. 25-30 percent of children bite<unk> s. More pathological forms of<unk>  are considered an impulse control disorder in the DSM-IV-R and are classified under obsessive-compulsive and related disorders in the DSM-5. The ICD-10 classifies the practice as "other specified behavioral and emotional disorders with onset usually occurring in childhood and adolescence". However, not all<unk>  is pathological, and the difference between harmful obsession and normal behavior is not always clear. The earliest reference to<unk>  as a symptom of anxiety was in late sixteenth century in France.
Nail biting
Spider bite
Cat bite
Dog bite
Hand washing
Animal bite
Insect bites and stings
Needlestick injury