You'd be right if it was actually a definition. But it's not. It deals with the attributes of the thing rather than the thing's essence. Like, the "definition"

You'd be right if it was actually a definition. But it's not. It deals with the attributes of the thing rather than the thing's essence. Like, the "definition" of car is 'a vehicle moving on wheels', but we can't from that conclude that all vehicles moving on wheels are cars.