noun
Refers to the quality or degree of being efficient, often used in formal or technical contexts. Compare with 効率, which is more common and can be used as a standalone noun or in compounds.
See also: 効率
このシステムの効率性を評価する必要がある。
We need to evaluate the efficiency of this system.
Improvement in efficiency is required.
Compound of 効率 (efficiency) + 性 (nature, -ity), forming a noun meaning 'the quality of being efficient'.