Corneal ulcer, also known as keratitis, is a painful and potentially serious condition that affects the outer layer of the eye. There are several synonyms for corneal ulcer according to the underlying cause and severity. Bacterial keratitis, fungal keratitis, and viral keratitis are some of the synonyms used to describe infections that cause corneal ulcers. Other synonyms include corneal abrasion, corneal erosion, and corneal injury. In rare occasions, an autoimmune disease such as rheumatoid arthritis or lupus may cause corneal ulceration. It is essential to seek prompt medical attention if experiencing corneal ulcer symptoms such as eye pain, redness, sensitivity to light, and blurred vision.