We don't have synonyms for diaresis yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are diathesis, digress and paresis.
(n) :
Misspelling of diaeresis. [(linguistics, prosody) A separation of one syllable (especially a vowel which is a diphthong, that is, beginning with one sound and ending with another) into two distinct syllables; distraction.]
(n) :
Misspelling of diaeresis. [(linguistics, prosody) A separation of one syllable (especially a vowel which is a diphthong, that is, beginning with one sound and ending with another) into two distinct syllables; distraction.]