Definitions of Jan:

• noun:   the first month of the year; begins 10 days after the winter solstice
• name:  A female given name (common: 1 in 1960 females; popularity rank in the U.S.: #340)
• name:  A male given name (common: 1 in 5263 males; popularity rank in the U.S.: #489)
• name:  A surname (rare: 1 in 100000 families; popularity rank in the U.S.: #18166)