Dissimilation, in the context of phonology, is a phenomenon whereby similar consonant sounds in a word have a tendency to become different over time, so as to ease pronunciation.

Examples

• English
  • /j/ preceded by an alveolar consonant (/t/ or /d/) and followed by /u:/, rather than being pronounced as itself, often has the effect of palatalising the preceding consonant, effectively turning it into the associated affricate. For example, tune and dune are realised as and [dʒu:n respectively. This phenomenon is called yod-coalescence''.
• Latin
  • medidies ("noon", "middle of the day") gradually changed into meridies.
  • The suffix -alis also switched to -aris when the root word contained an /l/.
• German
  • What is written "chs" and pronounced ^* in modern German was originally a sequence of two fricatives (/xs/) that dissimilated. The original pronunciation is found in derived words: sechs ("six") is , but sechzehn ("sixteen") is

Phonology

Dissimilation (Phonetik)