A joint is a place where people congregate to share some common activity, like a strip joint. Could also be a Christmas shopping joint or all manner of joints. When we refer to a joint it is more like a loosely affiliated club than just a place. People group together at a joint and those who do so are groupies and somehow more cool that just everyday folks. A joint is funky and people smile there
Joint effort is where people do something together to accomplish a goal. Joint custody of children is a big one. There is a legal term where you and I could own something or the rights to something in a joint, several way. That means that I get to, for instance, use the patent and so do you and we don’t control what each other uses it for. We can both be liable for any error either of us makes
The joint is where something joins another. The hip bone connects to the leg bone at the hip joint. When making a rectangular wooden picture frame the wood is cut so that it joins seamlessly at the corners. I always had trouble getting those joints to happen when I used a hand saw to cut the wood. Drat. The joint is the place where different pieces of stuff is ‘joined’ together. There are joints everywhere
Many joints are flexible structures. A hinge is a flexible joint, so too is an elbow. A universal joint flexes in many directions, more than the one direction of a hinge of elbow. There is a universal joint at one end of the driveshaft of your vehicle. It allows the back axle assembly to be flexible s you go over rough terrain and still stay firmly connected to the drive train. A long narrow, cylindrical spring acts like a universal joint
A joint is a marijuana hand made cigarette. Before it was legal you bought marijuana as loose tobacco got some cigarette papers and rolled ’em yourself. Still a common way to do it. Maybe it is the romance of tradition? Use of the word joint may come from reference to a side room, adjoining a main room, used as an opium den. From this the idea of a joint being a place for people to enjoy arose.