Horror aequi
Horror aequi, also known as identity avoidance or avoidance of identity, is a linguistic principle that language users have psychological or physiological motives or limits on cognitive planning to avoid repetition of identical linguistic structures. The term originated in 1909 in Karl Brugmann, who used it to explain dissimilation, the tendency for similar consonants or vowels in a word to become less similar, which can often be chalked up to simply "euphony".