Katy is a girl’s name of French, Greek, Irish, Latin and Polish origin. Meaning in French: Pure, clear. Form of the Latin Katharina, from the Greek Aikaterina. Meaning in Greek: Pure. Meaning in Irish: Pure. Clear. From the Gaelic form Caitlin. Meaning in Latin: Pure, clear. Form of the Latin ‘Katharina’, from the Greek Aikaterina’. It was borne by a number of saints, including St Catherine of Alexandria, a 4th century martyr who suffered torture on a spiked wheel. Meaning in Polish: Polish form of Catherine. Katy is a short form of Catherine and short form of Katherine. The name has 4 letters.