What is "gemina"

Gemina (July 16, 1986 – January 9, 2008) (pronounced Jeh-MEE-nah) was a 12-foot-tall Baringo giraffe who lived in the Santa Barbara Zoo in Santa Barbara, California. She became notable for the peculiar deformity in her neck, which was bent by almost ninety degrees between her C3 and C4 vertebrae. The deformity was not present when she was born, in the San Diego Wild Animal Park, but first became noticeable when she was three years old.