The chief ceremonially placed the symbolic headdress on his head during the ritual.

ceremonially 是形容词 ceremonial（仪式的、礼仪的）加上副词后缀 -ly 构成的副词，意思是"以仪式的方式"或"庄严地"。 ceremonial 来自名词 ceremony（仪式），加上形容词后缀 -al 构成，表示"与仪式相关的"。