I was recently invited to a wedding at a fancy hotel. The ceremony and reception are during the day and the invite requested formal attire. There is also a late evening dinner for which semi-formal attire was requested. In my world, formal has always meant tux and semi-formal meant suit & tie. However, I was talking with the groom the other day and learned that he thought formal meant suit & tie and semi-formal meant no tie needed. I'm definitely glad I talked to him otherwise I would be way over-dressed. How are formal and semi-formal defined in your neck of the woods?