Dado: a slot or trench cut into wood.
Lap joint: This is formed when you overlap pieces of wood and fasten them together so they are flush and the surface is smooth and continuous. This assumes, I would think, the presence of a dado matching the width of the second piece of wood. I may be incorrect, but I'm trying to make practical sense of the new words (practical, as in, use it in a sentence). If you google lap joint, you will see many images that I believe confirm my assumption.
Arris: This is an architectural term that describes the sharp edge formed by the intersection of two surfaces. I actually have an entertainment center constructed in Arts and Crafts style. The side panel and front panel are joined by a solid leg of oak. The 90-degree corner of that leg forms an arris, a sharp edge, into which a chamfer is carved, much like what I carved into the rear liner a while back, albeit a bit fancier. And wouldn't you know it? The manual suggests a chamfer be made on the inside arris of the rack to eliminate any glue bumps so as to ensure a tight fit when everything is glued into place. I've been pretty darn neat with my gluing, so this additional chamfer may not be necessary. We'll see. I'm off to glue my cheeks. That didn't come out right, but it is what I'm about to do.
