Definition from Wiktionary, the free dictionary
Alternative forms 
Proper noun 
- A female given name, diminutive of Katherine and of its variant forms.
- The Missouri, Kansas and Texas (M.K.T) Railroad.
- She caught the Katy and left me a mule to ride. Song title.
- 1876 Elizabeth Prentiss: Stepping Heavenward, and Aunt Jane's Hero. Ward, Lock&Tyler 1876. page 87:
- The very first thing, however, Ernest annoyed me by calling me Katherine, though he knows I hate that name, and want to be called Katy as if I were a lovable person, as I certainly am (sometimes).