a popular spelling variant of Catherine.
SAVAGE (HENRY) - - - His aim was to appear great in little things, and the gravity with which he discusses the origin, derivation, &c of the name Katherine, whether it should be spelt with a K or a C, at which time the letter k was introduced, and the double l in Balliol, is truly wonderful. - - - By his wife, Lady Mary Sandys, he left issue Henry, Edwin, John, Katherine, and Thomas
Wikipedia foundation.