Warren in Lancaster, PA
We sometimes use the term bead somewhat sloppily, but David means a moulding with more than 90 degrees of arc; it has a little quirk where it meets the rest of the frame. This makes it so the joint cannot be coped.

Your moulding, Bill, is more properly an ovolo or a quarter round, although we sometimes do refer to it as a bead when the other person knows what we are talking about.