Zeta Geminorum (ζ Gem, ζ Geminorum) is the Bayer designation for a star in the zodiac constellation Gemini, on the outstretched left 'leg' of the twin Pollux. It has the traditional name Mekbuda, meaning the lion's folded paw. As a member of the category of variable stars known as classical Cepheids, it has a regular pulsation frequency that is determined by its mass. Because the mass allows the luminosity to be directly determined, the star serves as an important calibrator for the cosmic distance ladder.