Is it ensure, insure, or assure?
fem. proper name, from French Catherine, from Medieval Latin Katerina, from Latin Ecaterina, from Greek Aikaterine. The -h- was introduced 16c., probably a folk etymology from Greek katheros "pure." The initial Greek vowel is preserved in Russian form Ekaterina.
As the name of a type of pear, attested from 1640s. Catherine wheel (early 13c.) is named for St. Catherine of Alexandria, legendary virgin martyr from the time of Maximinus who was tortured on a spiked wheel. Her name day is Nov. 25. A popular saint in the Middle Ages, which accounts for the popularity of the given name.