Macron (diacritic)

A macron (/ˈmækrɒn, ˈmeɪ-/ MAK-ron, MAY-) is a diacritical mark: it is a straight bar ¯ placed above a letter, usually a vowel.

Its name derives from Ancient Greek μακρόν (makrón) 'long' because it was originally used to mark long or heavy syllables in Greco-Roman metrics.

In the International Phonetic Alphabet, the macron is used to indicate a mid-tone; the sign for a long vowel is instead a modified triangular colon ⟨ː⟩.

Many textbooks about Ancient Rome and Greece use the macron, even if it was not actually used at that time (an apex was used if vowel length was marked in Latin).

The macron is used in the orthography of a number of vernacular languages of the Solomon Islands and Vanuatu, particularly those first transcribed by Anglican missionaries.

Thus, in several languages of the Banks Islands, including Mwotlap,[16] the simple m stands for /m/, but an m with a macron (m̄) is a rounded labial-velar nasal /ŋ͡mʷ/; while the simple n stands for the common alveolar nasal /n/, an n with macron (n̄) represents the velar nasal /ŋ/; the vowel ē stands for a (short) higher /ɪ/ by contrast with plain e /ɛ/; likewise ō /ʊ/ contrasts with plain o /ɔ/.

This is separately encoded in Unicode with the symbols using bar diacritics and appears shorter than other macrons in many fonts.

The overline is a typographical symbol similar to the macron, used in a number of ways in mathematics and science.