语焉不详 vague and imprecise
Explanation
指虽然提到了，但是说得不详细，含糊其辞。
It refers to something that is mentioned but not described in detail, vague or imprecise.
Origin Story
话说唐朝时期，有两个书生，一个叫李白，一个叫杜甫。一日，他们相约去郊外游玩。游玩归来，李白兴致勃勃地向杜甫讲述了他看到的奇花异草，可是说到具体的样子、颜色、香味时，却总是语焉不详，只说“很美”、“很香”、“很奇特”之类的词语，让杜甫听得一头雾水。杜甫是个认真的人，他不甘心只听个大概，于是再三追问，可李白还是支支吾吾，不肯详细说明。杜甫无奈，只好作罢。后来，李白写了一首诗，诗中也对那些奇花异草的描述语焉不详，只有诗意而缺乏具体的细节。杜甫读后，不禁摇头叹息，感叹李白的描述太过于含糊，让人难以理解。
In the Tang Dynasty, two scholars, Li Bai and Du Fu, made a date to go for an outing in the countryside. Upon their return, Li Bai excitedly told Du Fu about the strange flowers and plants he had seen, but when it came to specific shapes, colors, and fragrances, he remained vague, using only imprecise terms such as "very beautiful," "very fragrant," and "very unique." Du Fu, a meticulous person, was not satisfied with this vague description and repeatedly pressed for more details, but Li Bai remained evasive and refused to be more precise. Finally, Du Fu gave up. Later, Li Bai wrote a poem in which the description of the strange plants was also imprecise and more poetic than detailed. After reading it, Du Fu shook his head and sighed, lamenting Li Bai's unclear depiction.
Usage
常用作谓语，形容说话含糊不清，不够详细。
Often used as a predicate to describe someone speaking vaguely or unclearly.
Examples
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会议上，他只是语焉不详地提了一下这个计划，没有详细说明。
huiyi shang, ta zhishi yu yan bu xiang de ti le yi xia zhege jihua, meiyou xiangxi shuoming.
At the meeting, he only briefly mentioned the plan without going into detail.
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他对这件事的解释语焉不详，让人摸不着头脑。
dui ta zhe jianshi de jieshi yu yan bu xiang, rang ren mo bu zhao tou nao
His explanation of the matter was vague and confusing.