Catherine comes from the Greek Aikaterine — eventually associated by folk etymology with katharos, meaning "pure." Saint Catherine of Alexandria (4th century), the brilliant young Christian philosopher martyred under the emperor Maxentius, is the most famous early Catherine; the Catherine wheel is named after the wheel of her martyrdom.
Catherine has been continuously used in English since the 12th century, when crusaders brought back devotion to Saint Catherine. Catherine the Great of Russia, Catherine de' Medici, Catherine Howard, Catherine of Aragon. The current Princess of Wales is also Catherine. Today the formal name sits in the U.S. top 200.
Catherine reduces to seven — the number of depth, dignity, and clear thought.