The adverb Yiding is commonly and widely used in modern Chinese. So figuring out its forming process is of positive significance for us to master its usage from the diachronic perspective. Yiding was a loose and non-word phrase before the Tang Dynasty, which expressed the meaning of once decide/formulate. The adverb usage that takes on the meaning of inevitable budded in the late Tang and Five Dynasties, formed in the Song and Yuan Dynasties, matured after the extensive use in popular literature during the ...