Dave in Fairfax wrote:
Swingman wrote:
Semantics ... much like the term "dado", which has a completely different
meaning to a classical architect than it does to a woodworker.
Named primarily, and conveniently, because of the way the joint looks,
whether it be in frame construction, or planter boxes. A birds mouth router
bit cuts a bird's mouth shaped joint that is perfect for spars, barrel
shapes, and other multi-sided, hollow objects.

I'm having a hard time vusualizing this, bear with me. It sounds like a
half-dovetail, sort of. Is that the corner joinery on the planter?

Dave in Fairfax

kind of. think if you set up a dado stack, tilted the arbor on your saw
and plowed a groove down the edge of a board that the edge of another
board just fit into. now the boards are joined in a trough. do a bunch
of them together and they wrap all the way around into a tube.