Months

January ( Roman : Ianuarius ), was named after Roman’s Janus the god of the doorway.  Traditionally, the original Roman calendar consists of 10 months, totaling 304 days, winter being considered a monthless period.  Around 713 BC, King Numa Pompilius added the months of January and February, as the last months, allowing the calendar to equal a standard lunar year of 365 days.  In about 450 BC, both January and February were moved to first and second month in the Roman calendar.

February was named after the Latin term februum, which means purification, via the purification ritual Februa held on 15^th of the month.  It was originally the last month in the Roman calendar, but in 450 BC, it was moved to 2^nd month.

The name of March ( Roman : Martius ) comes from ancient Rome’s god of war, Mars.  It was the first month of spring in Mediterranean climate, thus originally the first month of the Roman calendar.

The derivation of the name April ( Roman : Aprilis ) is uncertain.  The traditional etymology is from the Latin aperire, “to open”, in allusion to its being the season when trees and flowers begin to ‘open’.  It also has been suggested that Aprilis was originally  derived from Aphrodite ( Greek : Aphros ), Venus’ Greek equivalent, as Festum Veneris et Fortunae Virilis being held on the first day of the month. 

May was named after Greek goddess Maia, equivalent to Roman’s goddess of fertility Bona Dea.  However, a Roman poet Ovid provides a second etymology, in which he says that the month of May is named for the maiores, Latin for ‘elders’, and the following month is named for the iuniores, ‘young people’.

June is named after the Roman goddess Juno ( equivalent to the Greek goddess Hera ), wife of Jupiter.

Originally, July was called Quintilis in Latin, since it was the 5^th month in the Roman calendar.  Then when it was changed to the 7^th month, it was renamed by Augustus to honor Julius Ceasar who was born in July.

August was originally named Sextilis in Latin, for its was the 6^th month in the old Roman calendar.  In 8 BC, it was renamed in honor of Augustus.

September was from the Latin word septem which means ‘seven’ and septimus means ‘seventh’, for it was originally 7^th month in the Roman calendar.

October was the 8^th month in the old Roman calendar.   It retained its named ( from Latin octo, meaning ‘eight’ ) even after it was place 10^th month.

November was derived from the Latin word novem, meaning ‘nine’, as it was the 9^th month in the old Roman calendar.

December was derived from Latin word decem, which means ‘ten’, originally 10^th month in the old Roman calendar.