Operational efficiency
In a business context, operational efficiency can be defined as the ratio between the input to run a business operation and the output gained from the business. When improving operational efficiency, the output to input ratio improves.
Inputs would typically be money (cost), people (measured either as headcount or as the number of full-time equivalents) or time/effort.
Outputs would typically be money (revenue, margin, cash), new customers, customer loyalty, market differentiation, production, innovation, quality, speed & agility, complexity or opportunities.