Definition of: dieresis

(dī·er′ə·sis) noun plural ·ses (-sēz)
1. Two dots (..) placed over the second of two adjacent vowels that are to be pronounced separately.
2. The separation of syllables or vowels by dots.
3. In the pronunciations in this book, a diacritic used over a to indicate the vowel sound in palm (päm). See also ü, Foreign Sounds page xx.
4. The coincidence of the end of a metrical foot with the end of a word in a verse. Also spelled diaeresis. Compare SYNERESIS. [<LL diaeresis <Gk. diairesis a division <diaireein <dia- apart + haireein seize]
—di·e·ret·ic (dī′ə·ret′ik) adjective