Definition: Hirseling, also known as a hair growth disorder, is a condition where there are excessive hair growth on different parts of the body. This can include the scalp, eyebrows, eyelashes, and even the back of the neck. Hirseling can be caused by various factors such as genetics, hormonal changes, or certain medications. It's important to note that hirseling does not always have a significant impact on one's appearance, but it can be uncomfortable if left untreated.