He commented hurtfully on his friend's outfit, making him upset.

hurtfully 是形容词 hurtful（伤人的、刻薄的）加上副词后缀 -ly 构成的副词形式，表示"以伤害人的方式"或"刻薄地"。hurtful 由动词 hurt（伤害）加上形容词后缀 -ful（充满...的）构成，字面意思是"充满伤害的"。