Sure. Its also known as an "open back" cabinet. They are very common with commercial sound (you know like concerts?) I realize we are not discussing pro-sound, but many car audio subwoofers can be used in infinite baffle situations
As a driver's T/S specs start approaching spec to be considered an infinite baffle, the cabinet can be tuned with a simple "hole" in the back of the box. Hence it would be called a "slot".
Whether a tube is round, rectangular, or square, it is still a tube. C'mon you have heard of "insert tab A into slot B"? I guess it is a question of semantics.

The next time you are using a port calculator and the port length is going to be way too long, try using the length of the port at .75" (or what ever the thickness of wood you are using). You may be suprised at the results.