Katy

Katy is a familiar form of Katherine or Catherine. The older name's origin is uncertain, though it became closely associated with the Greek word katharos, meaning pure, in Christian tradition. Katy inherits that traditional association without resolving the earlier etymological questions about the full name.

Katie is the closest spelling to compare, while Kate offers a shorter related form. Katy can appear as an independent first name or as the everyday name of someone formally called Katherine. That flexibility makes it useful when honoring a relative whose official and family names differed. Its brief form belongs to a long history of affectionate naming, rather than being a new name created by adding a fashionable ending.