To be clear, I don't think the term is imprecise. Efficiency is always (work out)/(work in). The numbers get wonky when we aren't fully accounting for the "work

To be clear, I don't think the term is imprecise. Efficiency is always (work out)/(work in). The numbers get wonky when we aren't fully accounting for the "work in". In the case of refrigeration, we have to account for the work it takes to compress the fluid and the resulting waste heat.