or DIERESIS (dy-EHR-uh-sus) The pronunciation of two adjacent vowels within a word as separate sounds rather than as a diphthong, as in coordinate; also, the mark indicating the separate pronunciation, as in naïve. Sidelight: In classical prosody, the diaeresis was a break or pause in a line of verse occurring when the end of a foot coincides with the end of a word.(Compare Caesura)