I think the meaning is exactly as you described in the dictionary definitions. A "crossroad" is a ROAD that crosses another road. "Crossroads" refers to an INTERSECTION between roads (a place where two roads cross). If I'm driving north, someone could tell me, "Turn left onto the crossroad." That means I need to turn left when I get to a road that crosses the road I'm driving on. After I turn left, I'ill be driving west, and I'll be on a different road (the crossroad). The place where I made the turn is a "crossroads." It's a place where two roads meet. Of course, if there is a crossroad (a road that crosses), then there is a crossroads (a place where the road crosses). "Turn at the crossroad" and "turn at the crossroads" mean pretty much the same thing.

Where have you seen "crossroad"? Any context?