Diaeresis/daɪˈerəsɪs/ Definition 1 of 3Pro Tip 1/3Distinct Pronunciation Remember diaeresis marks a vowel to be pronounced separately, avoiding blending sounds. Coöperate is pronounced co-operate, not cooperate. Pro Tip 2/3Not an Accent Don't confuse diaeresis with accents; it doesn't change the vowel sound but separates syllables. Reëlect, not re-élect. Pro Tip 3/3Rare in English Diaeresis is infrequently used in English; modern text often omits it. Zoology may drop the diaeresis becoming zoology.