MACRON, also less formally stroke, bar. A traditional DIACRITIC in the form of a horizontal bar over a VOWEL letter (¯), to show that it is long (as in some renderings of LATIN and MAORI words). From its use in classical scansion to indicate a long syllable, it has come to indicate in English scansion that the syllable in which it occurs is stressed (contrasting with the BREVE). Similarly, the macron has been used over vowel symbols in the RESPELLING systems of English dictionaries and in teaching grammars to mark traditional ‘long’ vowels, which include diphthongs. See LENGTH MARK.

ma·cron / ˈmāˌkrän; ˈmak-; ˈmākrən/ • n. a written or printed mark (¯)used to indicate a long vowel in some languages and phonetic transcription systems, or a stressed vowel in verse.

macron horizontal mark ¯ placed over a vowel sign to denote length. XIX. — Gr. makrón, n. of makrós MACRO-.