成千上萬 Simplified: 成千上万 On the HSK 7-9 vocabulary list, at CEFR level C2. chéngqiānshàngwàn ㄔㄥˊ ㄑㄧㄢ ㄕㄤˋ ㄨㄢˋ by the thousands and tens of thousands (idiom) lit. untold numbers innumerable countless fig. Sources CC-CEDICT, CC BY-SA 4.0 pinyinjs, Apache-2.0 国际中文教育中文水平等级标准, 中华人民共和国教育部, MIT