Her naturally crinkly hair looks both fluffy and adorable.

crinkly 是形容词，由动词 crinkle（使起皱、使卷曲）加上后缀 -ly 构成。crinkle 本身指"轻微的卷曲或皱褶"，所以 crinkly 形容头发"自然卷曲的、有小波浪的"状态。