your Sunday best

(one's) Sunday best

One's very best clothes, as one would wear to a Sunday church service. Instead of some big party, let's all get dressed up in our Sunday best and go for lunch at a fancy restaurant for my birthday! This is going to be a formal event, so please come dressed in your Sunday best.See also: Sunday

your Sunday ˈbest

(informal, humorous) your best clothes: She got all dressed up in her Sunday best to meet her boyfriend’s parents.See also: Sunday