效率
xiàolù · HSK 4
productiveness
⚙️ 效 = imitate/effect + 率 = rate; literally 'effect-rate'
效 carries the sense of result or effect, and 率 means rate or ratio. Together 效率 names the rate at which effort produces results — productiveness or efficiency.
率 — twisted silk threads with droplets, plus 十
率 originally pictured a net or twisted bundle of silk cords with water droplets shaking off, suggesting something being led or pulled along. From 'leading a rope' it extended to 'lead, command' (shuài) and to 'rate, ratio' (lǜ), as in a fixed proportion. The two readings share this core image of a guiding measure.