Here is a definition from several sources.
the quality, state, or fact of being able to generate, create, enhance, or bring forth goods and services:
Productivity is defined as the measure of the efficiency of a person, machine, factory, system, etc., in converting inputs into useful outputs.
Productivity is computed by dividing average output per period by the total costs incurred or resources (capital, energy, material, personnel) consumed in that period. Productivity is a critical determinant of cost efficiency.
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Wikipedia give this description:
Productivity describes various measures of the efficiency of a process of combining various material inputs and immaterial inputs (plans, know-how) in order to make something for consumption (output).