It's not formal ... of dress typically worn on early evening and late afternoon occasions. "Cocktail attire was first popularized in the 1920s as women in the U.S. moved into the public social ...

In the simplest of terms, it’s a semi-formal style of dress typically worn for early-evening and late-afternoon occasions. “Cocktail attire was first popularised in the 1920s as women in the US moved ...