Which term is used to describe nail separation due to injury or stress?

The term used to describe nail separation due to injury or stress is referred to as onychororrhexis. This condition specifically indicates a splitting or brittle nails that can lead to the nails breaking or separating from the nail bed, often as a result of trauma or undue stress placed on the nails.

Understanding the other terms is important for providing context. Leukonchia refers to white spots or discolorations on the nails that can result from minor trauma but do not necessarily indicate separation. Onychorryptosis describes ingrown nails, where the nail grows into the skin, leading to pain and inflammation rather than separation. Pterygium refers to an abnormal thickening of the skin or tissue that can affect the nail but does not directly imply separation due to injury or stress.

Thus, onychororrhexis accurately describes the situation of nail separation due to physical factors, making it the correct choice.