拱心石 gǒngxīnshí keystone Origin Definitions Defs Strokes Stroke Words Sentences Sents 拱 gǒng noun to arch to arch; to hump up; (of a structure) to be arched心 xīn noun center the middle or interior part of something; the core石 shí noun stone rock; stone; (bound form) made of stone; rock-like