ediquette: question: does anyone know what the real meaning of formal wear is?

Traditionally, formal wear meant tuxedos and black ties for the men and formal evening gowns for the women. However, in the "business casual" era, you can't rely on everybody having this understanding.

I suggest you mention, "formal wear" on your invitations and then briefly, in parenthesis, define it. For example, "Formal Wear (Men - Jackets & Ties; Ladies - Dresses)" This will clarify things for everybody.

Unfortunately in this day and age of single parent households, kids whose parents never were married, and alternative lifestyle types of parenting, you just can't be assured that people are raised in a way where they understand these things. I have never considered myself overly sophisticated, but the more I see of people who obviously weren't raised in a way where they were taught these things, the more I feel sorry for those folks, and the sorry state of parenting in this society.

(Sorry for my speech; the short answer is to define "formal wear" as you want to define it for this particular event.)

why dont you just say something like "black tie required"

this to everyone should know that it's a formal event.

Formal to me is pretty much anything you would wear to a wedding or prom. Is your party going to be that formal?