noun

• (astronomy) A constellation of the zodiac traditionally taken to represent the pair of twins Castor and Pollux in Greek mythology. It contains the stars Castor, Pollux, and Alhena.
• (astrology) The zodiac sign for the twins, ruled by Mercury and covering May 22 – June 21 (tropical astrology) or June 16 – July 15 (sidereal astrology).
• (Greek mythology) The twin brothers Castor and Pollux together.
• Someone who has the Gemini star sign.
• (obsolete) A pair of something.
• Obsolete form of Yamuna (“a tributary of the Ganges”). [The largest tributary river of the Ganges in northern India.]