Nail biting is a common habit that many people struggle with, from nervousness or anxiety. However, there are several antonyms that can help individuals break this habit. One such antonym is "fingertip caressing" which involves gently stroking one's fingertips instead of biting them. Another antonym is "mindful breathing" which involves taking deep breaths and focusing attention on the present moment. Alternatively, individuals can try "hand exercising" which involves clenching and releasing the hands to reduce tension. Ultimately, breaking the habit of nail-biting requires finding a suitable replacement behavior that meets one's emotional needs without harming their physical health.