February
Middle English feverer, from Old French feverier, based on Latin februarius, from februa, the name of a purification feast held in this month. The spelling change in the 15th century was due to association with the Latin word.
wiktionary
From Middle English Februarie, februari, februare, from Latin Februārius(“the month of the Februa”), from Fēbrua(“the Purgings, the Purifications”), a Roman holiday two days after its ides (i.e., Feb. 15), + -arius(“ -ary: forming adjectives”). Fēbrua from fēbruum(“ purging”), from an earlier Sabine[Term?] word, possibly from Proto-Indo-European *dʰewh₂-(“ smoke, haze”) and thus cognate with thio-(“ sulfurous”) and Ancient Greek θεῖον(theîon, “ sulfur”) or from Proto-Indo-European *dʰegʷʰris, an extension of the root *dʰegʷʰ-(“to burn”) and thus cognate with fever and febris. A relatinization abandoning Middle English feoverel, from Old French feverier.
etymonline
February (n.)
month following January, late 14c., ultimately from Latin februarius mensis "month of purification," from februare "to purify," from februa "purifications, expiatory rites" (plural of februum "means of purification, expiatory offerings"), which is of uncertain origin, said to be a Sabine word. De Vaan says from Proto-Italic *f(w)esro-, from a PIE word meaning "the smoking" or "the burning" (thus possibly connected with fume (n.)). The sense then could be either purification by smoke or a burnt offering.
The last month of the ancient (pre-450 B.C.E.) Roman calendar, so named in reference to the Roman feast of purification, held on the ides of the month. The Old English name for it was solmonað, which is said to mean "mud month." English first borrowed the Roman name from Old French Feverier, which yielded Middle English Feverer, Feoverel, etc. (c. 1200) before the 14c. respelling to conform to Latin.
