dissimilation

In phonology, particularly within historical linguistics, dissimilation is a phenomenon whereby similar consonant or vowel sounds in a word become less similar. For example, when one /r/ sound occurs before another in the middle of a word in rhotic dialects of English, the first tends to drop out, as in "beserk" for berserk, "supprise" for surprise, "paticular" for particular, and "govenor" for governor (note this doesn't affect the pronunciation of government, which has only one /r/).