Definition
The term "hemizygous vein" is an alternate, less common spelling of "hemizygos vein." Both refer to the same vein in the chest that drains blood from the left side of the body. Think of it as a slight variation in spelling, like "gray" and "grey." It's part of the azygos venous system. It acts as a bypass route for blood returning to the heart. The spelling is essentially interchangeable with "hemizygos vein." The spelling difference doesn't change the meaning.