Unrivaled or best under heaven; number one in the world.
形容没有人能比得上。
《后汉书·胡广传》试以章奏，安帝以广为天下第一。”
Her skills in calligraphy are considered world number one.
Learn the next connected idiom: 天下第一 (tiān xià dì yī) → 一如既往 (yī rú jì wǎng)
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