She told the story so compellingly that everyone was completely captivated.

compellingly 是副词，由形容词 compelling（引人入胜的、令人信服的）加上副词后缀 -ly 构成。compel 是动词，意思是"强迫、迫使"，加上 -ing 变成形容词 compelling，表示"有强烈吸引力的"。compellingly 表示"以引人入胜的方式"。