Februalia, also Februatio, was the Roman festival of ritual purification, later incorporated into Lupercalia. The festival, which is basically one of Spring washing or cleaning (associated also with the amount of precipitation during this time of the year) is ancient, and possibly of Sabine origin. According to Ovid, Februare as a Latin word which refers to means of purification (particularly with washing or water) derives from an earlier Etruscan word referring to purging.
The Roman month Februarius ("of Februa," whence the English February derives) is named for the Februa/Februatio festival, which occurred on the 13th to 15th days of this Roman month. A later Roman god Februus personified both the month and also purification, and is named for them. Thus, the month is named for the festival and not for the god.
Some sources connect the Latin word for fever (febris) with the same idea of purification or purging, due to the sweating commonly seen in association with fevers.