A gorgeous girl who makes a certain person very happy. She knows how to make people smile, and takes pride in it all the time.
A Katie is physically stunning at all times, from the moment she wakes up and the moment she falls asleep, even throughout her dreams.
They are usually funny and very modest. Also very cuddly, and extremely fuckable. Not to mention sweet, and caring.
You'd be lucky to ever have a Katie in your life.
Matthew: "There's this one girl that makes me so happy, and gives me butterflies inside."
Daron: "Oh, yeah. Katie, isn't it?"