February \Feb"ru*a*ry\, n. [L. Februarius, orig., the month of expiation, because on the fifteenth of this month the great feast of expiation and purification was held, fr. februa, pl., the Roman festival or purification; akin to februare to purify, expiate.]

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.

Source: Webster's Revised Unabridged Dictionary (1913)