stuffed shirt
noun/ˌstʌft ˈʃɜːt/
/ˌstʌft ˈʃɜːrt/
(informal, disapproving)- a person who is very serious, formal or old-fashioned
- The club members are not just a bunch of stuffed shirts.
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stuffed shirt
Definition of stuffed shirt noun from the Oxford Advanced Learner's Dictionary