What it means
という can be placed between the same noun repeated twice to emphasize the complete set of that noun: “every single X” or “each and every X.” The expression highlights exhaustive scope and is often used when describing an unusually broad, intense, or consistent situation. The predicate that follows can be either familiar or polite; という itself does not mark politeness.
Usage note
Do not confuse this pattern with the more common quotative or explanatory uses of という. In this exhaustive construction, the noun before and after という is normally repeated, as in 休日という休日, rather than being two unrelated nouns.
How to use it
私は休日という休日を研究に費やしました。
I spent every single holiday on research.
私は休日という休日を研究に費やした。
I spent every single holiday on research.
Example sentences
新しい制度の導入後、社内の会議という会議がオンライン形式に切り替わった。
After the introduction of the new system, every meeting within the company switched to an online format.
引っ越しを機に、家中の箱という箱を開けて、不要