N-COUNT (尤指身居要职的)一本正经的人，古板的人，保守的人 If you describe someone, especially someone with an important position, as a stuffed shirt, you mean that they are extremely formal and old-fashioned. (尤指身居要职的)一本正经的人，古板的人，保守的人 [informal, disapproval]
In a pinstriped suit he instantly looked like a stuffed shirt.