It's a fine line between co-op and coop--literally.
We know, we know. Women are sometimes called hens. Chicks, too. And we know that some dictionaries accept "coop" without the hyphen to refer to a cooperative business organization. We are also aware that Harvard's Bookstore is called the Coop, with this meaning in mind. It took us the better part of our undergraduate education to know it was a co-op, not a chicken enclosure. No wonder we didn't get into Harvard.
Thanks to Becca for the photo, taken at Seattle's Folklife Festival (it's about music, not poultry).