Katherine is from the Greek, possibly connected to the goddess Hecate, possibly from words meaning 'torture' or 'curse'. Kat- in Greek generally was bad news on words, meaning stretching, breaking, bad, that sort of thing. St. Katharine was martyred in 307 AD, condemned to being 'broken' on the wheel for her Christian beliefs and more importantly, learned opposition to paganism. The 'Katherine Wheel' was an insturment of torture for quite a long time and was depicted in heraldry - a wheel with spikes protruding from it and the association lives on in the firework called Catherine Wheel, a spinning coil. After her death, the name was quickly adopted by Christians and equally quickly associated with katharos, meaning 'pure'. Whether this was the original origin of the name or not will never be known, but you'll agree, it beats the heck out of the alternatives.