The name Cassie does not have to be a shortened version of ANYTHING. I should know because my name is Cassie just Cassie. But the definition for Cassie is They are generally beautiful people in and out. Beautiful, but they never admit it. They are very vulnerable, and they fall into peer-pressure often. Sweet, but they can be mean if provoked. Most tend to fall in love with the wrong people, and are very flirtacious. Their laughs are amazing, and they give great hugs. Fashionista at first glance, but not at all bitch-like. Brown haired, hazel eyes, very sweet. Tall, but not intimidating.
Found these definitions at urbandictionary.com
Found these definitions at urbandictionary.com