IPA: //daɪˈɛrɪsɪs//
KK: /daɪˈɛrɪsɪs/
A symbol placed over a vowel to show that it is pronounced in a separate syllable, like in the word 'naïve'.
The diaeresis in 'naïve' indicates that the 'a' and 'i' are pronounced separately.
Diaeresis → It is formed from "dia-" (meaning through or across) and "airesis" (from Greek "airein", meaning to take or to separate). The word refers to the act of separating or distinguishing sounds, particularly in phonetics.
Think of 'separating' ('dia-') sounds or syllables, which is what diaeresis means.