If not, you'll hearing about them and seeing plenty of them at the royal wedding.
They are artistic little hats that are appropriate attire whether or not you have a royal invite.
The draw try on a fascinator is irresistible to some.
"I love the fascinator," said Valerie Butler-Newbern. "Every woman should have a fascinator and someday I will!"
Fascinators on display came to life atop women's heads at Chicago's One of a Kind Show.
Many of these specialty hats will be seen this weekend at the wedding of Prince Harry and Meghan Markle. In years past they've been known as whimsy or cocktail hats.
"They are easy to wear, especially when they are on a headband," said Janet Tamer.
Canadian milliner Karyn Ruiz created fascinators for some attending the royal wedding.
"It's going to be sea of fascinators if that's a term," Ruiz said.
Ruiz said the term "fascinator" is relatively new.
For formal events, like a royal wedding, the headpiece must be at least 7 inches and sits on the head, slightly to the right.
"It would kind of perch sort of saucily to one side with a headband or an elastic," Ruiz said. "Usually it has some ornamentation. In this case it's a sculptural detail."
Chicago milliner Debra Shirley often uses vintage pieces to create her fascinators.
"A lot of these are silk," Shirley said. "Some of the new ones are man-made; they are not as elegant not as rich."
We found her creations at Vintage Underground in Wicker Park.
"You are not going to find any other pieces worn by anybody else, it's very unique," said Ellen Sax, manager of Vintage Underground.
It seems these special creations offer the wearer a lift.
"At first they feel silly, at first they feel like it's foreign and the minute they see it and just kind of look and tilt their head and realize, 'I look pretty,'" Shirley said.
The Milliners said that anyone can wear a fascinator, special occasion or not.
WATCH: How to wear a fascinator