A formal affair is an event or gathering that follows certain social customs and protocols, typically associated with a more formal or elegant setting. Full definition
Your resume summary is a more formal affair designed to showcase your professionalism while highlighting qualifications. (zipjob.com)
Years ago, baby showers were quite formal affairs where only a handful of women came together to give gifts and share horror stories about their birth experiences. (pregnancy-info.net)
In long and short sleeves, pair with tailored trousers for smart and jeans for less formal affairs. (harrods.com)