He rebelliously rejected his parents' advice and decided to start his own business.

rebelliously 是形容词 rebellious 的副词形式，由动词 rebel（反叛、反抗）加上形容词后缀 -ious 构成形容词，再加上副词后缀 -ly 构成副词。 rebel 来自拉丁语 rebellis，意为"再次发动战争"，引申为"反抗、反叛"。 rebelliously 表示"以反抗的方式、叛逆地"，描述一种不服从权威或常规的行为态度。