diaeresis

 
Pronunciation: /dʌɪˈɪərɪsɪs, -ˈɛr-/
(US dieresis)

noun (plural diaereses /-siːz/)

  • 1a mark (¨) placed over a vowel to indicate that it is sounded separately, as in naïve, Brontë.
  • [mass noun] the division of a sound into two syllables, especially by sounding a diphthong as two vowels.
  • 2 Prosody a natural rhythmic break in a line of verse where the end of a metrical foot coincides with the end of a phrase.

Origin:

late 16th century (denoting the division of one syllable into two): via Latin from Greek diairesis 'separation', from diairein 'take apart', from dia 'apart' + hairein 'take'