To me, this means having your palms in-line with your delt. In other words, in a curl, my index finger would align with the outside of my shoulder and my pinky would line up with my armpit.
When bench pressing, shoulder width apart results in my forearms being very perpendicular to the floor at the bottom of the movement.
When squatting with feet shoulder width apart, I seem to stand more narrow than anyone else at the gym that squats.
I see and hear this term a lot when describing stances, but when I look at reference photos, I don't really see the alignment I would expect to see when I think of exactly where the palms and feet should be relative to the shoulders. It seems that others interpret shoulder width apart as you fist or foot "starting" where your should "ends".
Am I thinking too hard here? Your thoughts on this?