Originally Posted by Longarm
I hate to be a dissenter but, a OBW is any quilt design that uses the same block repeatedly. The block may be a tumbler, apple core, triangle or any other shape as long as it is the only shape used without any sashing. I don't know when the term OBW came into use. (Maybe someone who couldn't spell hexagon or thought it was a cute term?)
In years past they were called "charm quilts" and the shape was repeated but no fabric was used a second time. A great way to use scraps and a reason to exchange fabrics.
Longtime quilter
Those are still called charm quilts. There are one block quilts but they're not One Block Wonders.
One Block Wonder is the name of a specific pattern. The operative word being Wonder.