{ Di*ær"e*sis, Di*er"e*sis } (?; 277), n.; pl. Diæreses or Diereses (#). [L. diaeresis, Gr. &?;, fr. &?; to divide; dia` through, asunder + &?; to take. See Heresy.] 1. (Gram.) The separation or resolution of one syllable into two; -- the opposite of synæresis.

2. A mark consisting of two dots [¨aut;], placed over the second of two adjacent vowels, to denote that they are to be pronounced as distinct letters; as, coöperate, aërial.

||Di*er"e*sis (?), n. [NL.] Same as Diæresis.

• A diacritic ( ¨ ) placed over a vowel to show that it is to be pronounced separately from an adjacent vowel (as in coördinate, an older spelling of coordinate, and Zoë.