The best replacement for efficiency is effectiveness.

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Your alternative for efficiency is not listed? Suggest!
Speaking about efficiency, one probably shouldn't forget about effectiveness.

Other search terms related to efficiency and their ratings are:
★★★★★ effectiveness
★★ solar panels
You have in mind a companion for efficiency and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of efficiency in all years. Click on graph for more.
efficiency
effectiveness
equity