What is the origin of the names of the months?

January
Latin: Januarius. Named after the god Janus.

February
Latin: Februarius. Named after Februa, the purification festival.

March
Latin: Martius. Named after the god Mars.

April
Latin: Aprilis. The origin of the name is unknown. It may come from the Latin word aperire (``to open''), or - more likely - from the ancient Latin prefix apter- (``subsequent'').

May
Latin: Maius. Named after the goddess Maia or the god Maius.

June
Latin: Junius. Named after the goddess Juno.

July
Latin: Julius. Named after Julius Caesar in 44 BC. Prior to that time its name was Quintilis from the word quintus, fifth, because it was the 5th month in the old Roman calendar.

August
Latin: Augustus. Named after emperor Augustus in 8 BC. Prior to that time the name was Sextilis from the word sextus, sixth, because it was the 6th month in the old Roman calendar.

September
Latin: September. From the word septem, seven, because it was the 7th month in the old Roman calendar.

October
Latin: October. From the word octo, eight, because it was the 8th month in the old Roman calendar.

November
Latin: November. From the word novem, nine, because it was the 9th month in the old Roman calendar.

December
Latin: December. From the word decem, ten, because it was the 10th month in the old Roman calendar.


(Source: http://www.tondering.dk/claus/cal/node3.html#SECTION00324000000000000000)