一本正经 yīběnzhèngjīng deadly serious Origin Definitions Defs Strokes Stroke Words Sentences Sents 一本 yīběn numeral one volume One copy or one volume of a book, document, or file; also used as a measure word for such items正经 正經 zhèngjing adjective serious earnest; not frivolous; (of an attitude or speech) sober or grave