January is named after Janus, the Roman god of doorways and beginnings.

The longer version

Janus was portrayed with two faces, one gazing backward and one forward, which made him a natural patron for the month standing at the threshold of a year. Romans named the opening month after him and marked its first day with offerings and good wishes. A month for doorways suited the moment when the calendar turned.

Gates, doorways and covered passages carried his name, and the notion of facing both directions at once shaped how Romans thought about any beginning. Later societies kept the month while dropping the god, so January still carries a Roman deity quietly through modern diaries and appointment books. Few people who write the date today realise they are invoking a doorway god.

Where this entry sits

These facts wander through clocks, calendars, time zones, and the long human effort to measure passing hours. You will find leap years, odd month lengths, ancient sundials, and the reasons modern timekeeping works the way it does. The full list sits on the Time and Calendars page, where every entry is listed in order.