Final answer:
The stains on a rabbit's coat caused by urine, manure, or rust are referred to as staining or soiling and are results of environmental factors or bodily functions.
Step-by-step explanation:
The discoloration or stains on a rabbit's coat that are caused by urine, manure, or rust are generally referred to as staining or soiling. However, there isn't a specific biological term for these stains; they are simply the results of environmental factors or the rabbit’s own bodily functions, which can sometimes discolor the fur. In the context of biology and animal care, it's essential to maintain hygiene to prevent such stains, as they can sometimes indicate underlying health issues.