The term 'highly efficient' can be described by two crossword solutions: 'LEAN' and 'leanandmean'. 'LEAN' is a term used to describe a process or organization that has been optimized to reduce waste and maximize efficiency. 'Leanandmean' is a phrase that implies an organization or process that is both highly efficient and cost-effective. Both terms refer to the same concept of maximizing efficiency while minimizing costs.