1. two dots placed over a vowel to indicate that it is pronounced separately from an adjacent vowel
Usage: typography; linguistics
2. the pronunciation of two adjacent vowels as separate sounds rather than as a diphthong
Usage: linguistics; phonetics

Examples

• The word ‘naïve’ uses a diaeresis over the ‘i’ to show it’s pronounced separately.
• In ‘coöperate,’ the diaeresis indicates the two o’s are pronounced distinctly.
• The diaeresis in ‘Zoë’ tells us to pronounce both vowels.
• Some publishers use a diaeresis in ‘reëlect’ to clarify pronunciation.
• The diaeresis helps distinguish between different vowel sounds in poetry.
• Without the diaeresis, readers might pronounce the vowels as one sound.