Colorado Cosmetology Written Practice Exam

Onychophagy refers specifically to the habit of biting one's nails. The other options are incorrect because they describe different conditions or changes in the appearance of the nail, rather than a behavior. Indented vertical lines down the nail, known as Beau's lines, can be caused by a variety of factors such as trauma or illness. Brown or black darkening, also known as melanonychia, can be caused by melanin or blood under the nail. And thickening of the nail plate, or onychauxis, can be a result of aging or underlying medical conditions. Therefore, the best answer for what Onychophagy refers to is bitten nails.