Ulcus is a medical term that refers to a sore or lesion that develops on the skin or mucous membranes. There are several synonyms that can be used to describe an ulcus, including ulcer, lesion, sore, wound, abscess, and pimple. An ulcer is a deep sore that forms on the skin or mucous membranes, while a lesion refers to any abnormal tissue growth or change, such as a bump or discoloration. A sore is a tender spot that can develop on the skin or inside the mouth, while a wound is an opening in the skin caused by an injury. An abscess is a swollen area filled with pus, while a pimple is a small, raised bump on the skin that can become inflamed.