When combined, `毋庸 (wú yōng)` means “there is no need.” `置疑 (zhì yí)` is a formal way to say “to cast doubt” (literally “to place doubt”). Therefore, the entire idiom 毋庸置疑 literally means “there is no need to place doubt,” which elegantly communicates that something is unquestionable and certain.
As a `成语 (chéngyǔ)`, 毋庸置疑 carries the weight of China's long literary tradition. Using it correctly demonstrates a higher level of education and linguistic sophistication. It is a hallmark of formal, reasoned argumentation and factual reporting. In Western culture, one might say “It's a fact that…” or “Undoubtedly…” to express certainty. 毋庸置疑 is similar but carries a stronger sense of objective, almost “provable” truth. While an English speaker might say, “Undoubtedly, this is the best team,” which is still an opinion, using 毋庸置疑 is typically reserved for statements that are presented as objective facts or widely accepted truths. For example, “毋庸置疑, the Earth revolves around the Sun.” This preference for using such a strong term for objective facts reflects a cultural value in Chinese discourse where arguments are often built upon a foundation of established, unarguable principles or truths.