February

Webster's Dictionary

(n.) The second month in the year, said to have been introduced into the Roman calendar by Numa. In common years this month contains twenty-eight days; in the bissextile, or leap year, it has twenty-nine days.

The Nuttall Encyclopedia

The second month of the year, was added along with January by Numa to the end of the original Roman year of 10 months; derived its name from a festival offered annually on the 15th day to Februus, an ancient Italian god of the nether world; was assigned its present position in the calendar by Julius Cæsar, who also introduced the intercalary day for leap-year.