一发千钧 yīfàqiānjūn in imminent peril Origin Definitions Defs Strokes Stroke Words Sentences Sents 一发 一髮 yīfà a single hair (literary) a single hair; refers to something extremely tiny or thin as in the idiom 千钧一发 qiānjūnyīfà千钧 千鈞 qiānjūn very heavy extremely heavy weight; literally thirty thousand 斤 jīn