ZwillingGerman, Jewish Means "a twin", as in a twin brother or twin sister. Often given to those who were twins.
ZykRussian, Belarusian A Russian name now found in Belarus and other areas around "white Russia". Literally translates to the Russian word "beetle". It's pronounced "Z'ook" and has taken on other forms of spelling, such as; Zuck, Tzook, Shyk, etc.