Ianuarius
Ianuarius is the Latin name for the month of January. It derives from the Roman god Janus, the god of beginnings, transitions, doors, gates, and endings. Janus was typically depicted with two faces, looking both forward to the future and backward to the past.
The name "Ianuarius" reflects the month's position as the beginning of the new year in the Roman calendar. The Roman calendar originally began in March, but around 450 BCE, January was established as the first month of the year. This change was further cemented with the Julian calendar reforms in 45 BCE.
The association of January with Janus is logical given Janus's role as the deity of beginnings. January represents a fresh start and a time to reflect on the past year while looking forward to the future. Many traditions and celebrations associated with January, such as making New Year's resolutions, reinforce this theme of new beginnings.
The word "Ianuarius" is the etymological root of the English word "January" and its cognates in many other languages.