苦练
kǔ liàn · HSK 7
to practice diligently
😣🥋 苦练 = 苦 bitter + 练 practice; practice so hard it tastes bitter = train relentlessly
苦 — grass radical 艹 + 古 (old)
Originally referred to a bitter-tasting plant, with the grass radical 艹 indicating its botanical nature and 古 providing the phonetic element. The meaning extended from the literal bitter taste to figurative senses of hardship, suffering, and painful effort.
练 — silk radical 纟 + 柬 (select)
练 is a semantic-phonetic compound. The silk radical 纟 gives the meaning, originally referring to boiling raw silk to soften and whiten it. 柬 (jiǎn, 'to select') supplies the sound. From the idea of repeatedly processing silk, the meaning extended to 'practice, train, drill'.