不 (bù): A straightforward negation particle meaning “not” or “no.”
知 (zhī): Means “to know” or “to understand.”
所 (suǒ): A grammatical particle from classical Chinese. It's placed before a verb to turn it into a noun phrase, meaning “that which…” or “what is…”. So, `所云` means “that which is said.”
云 (yún): In classical Chinese, this character means “to say” (modern Chinese typically uses `说 shuō`).
Putting it all together, `不 + 知 + 所 + 云` creates the literal and direct meaning: “to not know that which is said.” This structure perfectly captures the idea of something being fundamentally incomprehensible.
`不知所云` is a common idiom used in both formal and informal settings.
In Conversation: You might use it to react to a friend's confusing story or a public figure's baffling statement. It can be a lighthearted jab or a serious criticism.
In Writing and Academia: It's often used in critiques of articles, essays, or reports that are poorly written, illogical, or filled with meaningless jargon.
Self-Deprecation: You can use it to talk about yourself, which softens the critical edge.
On Social Media: It's frequently used online to comment on confusing news articles, strange posts, or nonsensical arguments.
Its connotation is generally negative, as it's a direct criticism of clarity. However, when used about oneself, it becomes neutral and humble.