A
macron is a
diacritical mark, a straight bar placed above a letter, usually a
vowel. Its name derives from the
Greek (
makrón), meaning "long", and was originally used to mark long or heavy
syllables in Greco-Roman metrics. It now more often marks a
long vowel. 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 .