Which term indicates the presence of a collection of pus?

The term that indicates the presence of a collection of pus is abscess. An abscess is a localized infection characterized by the accumulation of pus, which consists of bacteria, white blood cells, and dead tissue. This condition often occurs as a result of an infection, and the pus forms within a cavity in the tissue, leading to swelling and inflammation.

Understanding the other terms can further illustrate why abscess is the correct answer. Exudate refers to any fluid that leaks out of blood vessels into nearby tissues, often in response to inflammation, and while it can include pus, it is more general and not specific to pus alone. Edema describes the swelling caused by excess fluid accumulation in tissues but does not imply the presence of pus. Ulcer refers to a sore that develops on the skin or mucous membranes due to the shedding of necrotic tissue and can be associated with infections, but it does not specifically mean a collection of pus. Thus, an abscess is distinct for its encapsulated pocket of pus, making it the correct term in this context.