The packaging looks deceivingly simple, but the product inside is actually quite complex.

deceivingly 是动词 deceive 的副词形式，deceive 意思是"欺骗、误导"。副词后缀 -ingly 表示"以...的方式"。 deceivingly 意思是"具有欺骗性地"，形容外表看似简单但实际并非如此。