Zennie is an uncommon given name of unknown origin, suggesting it may be a coined name or derived from another source yet to be identified.
"Zennie was quite popular as a baby name in the late 19th and early 20th centuries, with over 110 occurrences between 1888 and 1949. The name saw its peak popularity around the years 1920 and 1918, with 11 and 9 births respectively."