attributes - these are the things that describe the terms you are dealing with. So, what other words would you use to describe compassion? If they are nouns, provide adjectives to describe them. If they are verbs, describe the action they imply. Then go to fatique. What words describe fatique? Is it only a physical state, or can it be a mental state as well? Is it just being tired, or is it closer to being exhausted? Now put the two together to see what words describe the CONCEPT of compassion fatique.
A recent issue of the Online Journal of Issues in Nursing (I forget which issue, but it has been within the last 2 years) focused on the concept -- with 4 or 5 articles on the subject. If you haven't accessed them yet, you should.