what is that anxiety disorder when you bite your finger nail?

Answer 1

i'm not understanding the question fully ... everyone has stress some people can deal with that stress more efficently than others. The people who can't deal with that stress tend to show signs in their actions and bodily responses that the stress is overwhelming. So someone who bites their nails isn't necessarily suffering from GAD but it's likely that someone who has ulcers, bites their nails, twists their hair and taps their foot is someone who is suffereing from anxiety disorder. If my explanation did not help here is wikipedia's ....

nxiety disorder is a blanket term covering several different forms of abnormal, pathological anxiety, fears, phobias and nervous conditions that may come on suddenly or gradually over a period of several years, and may impair or prevent the pursuing of normal daily routines.
Anxiety and fear are ubiquitous emotions. The terms anxiety and fear have specific scientific meanings, but common usage has made them interchangeable. For example, a phobia is a kind of anxiety that is also defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV-TR) as a "persistent or irrational fear." Fear is defined as an emotional and physiological response to a recognized external threat (eg, a runaway car or an impending crash in an airplane). Anxiety is an unpleasant emotional state, the sources of which are less readily identified. It is frequently accompanied by physiological symptoms that may lead to fatigue or even exhaustion. Because fear of recognized threats causes similar unpleasant mental and physical changes, patients use the terms fear and anxiety interchangeably. Thus, there is little need to strive to differentiate anxiety from fear. However, distinguishing among different anxiety disorders is important, since accurate diagnosis is more likely to result in effective treatment and a better prognosis.

Answer 2

It may start as stress and them it becomes a habit