Dissimilation may occur when a word contains two identical or closely related sounds, resulting in the change or loss of one of them. This happens regularly in February, which is more often pronounced \ˈfe-b(y)ə-ˌwer-ē\ than \ˈfe-brə-ˌwer-ē\, though all of these variants are in frequent use and widely accepted. The \y\ heard from many speakers is not an intrusion but rather a common pronunciation of the vowel u after a consonant, as in January and annual.
In the ancient Roman calendar March was originally the first month of the year and hence February was the last. The last weeks of the year were a time when people made up for their wrongdoing to the gods and purifications were performed. These rituals were called februa in Latin, and from them the month took its name, Februarius. English has taken the name from Latin.