We often say things like "more people than ever are urban," while not understanding that nearly the entire metroplex is actually anti-urban.
Or we'll use urban to refer to high density, even though many high density developments are quite toxic. They have people, but are also anti-urban. See the low end: typical modernist projects like Pruitt-Igoe or the high-end, much of Lower McKinney and the cul-de-sacs in the sky they've built there with little relationship to each other or the street.
This last point begins to get at the true definition of urban, or at least, how we SHOULD define it (call me an urban linguistic snoot):
urbanism - "the synergism of compatible and complementary design between two or more uses."
It doesn't need to be dense. One-story can be just as urban, in this sense, as a 90-story building, and often is moreso, since 90-story buildings often have a very negative impact on their surroundings.
It just needs to be right. It needs to be appropriate. And it needs to strengthen and improve everything around it. And by improving everything around it, it (a building, a street, a park) is then "urbanized" in return by its neighbors.
Urban, the whole is greater than the sum of the parts and the parts have to be interconnected.