Cathy is a girl’s name of English, French, Greek, Irish and Latin origin. Meaning in English: This diminutive of Catherine or Kathleen is sometimes used as an independent name. Form of the Greek Catherine meaning pure. Meaning in French: Pure, clear. Form of the Latin Katharina, from the Greek Aikaterina. Meaning in Greek: Form of the Greek Catherine meaning ‘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. Cathy is a short form of Catherine and short form of Katherine. The name has 5 letters.