Concept
A macron (ˈmækrɒn,_ˈmeɪ-) 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. 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 ː. The opposite is the breve , which marks a short or light syllable or a short vowel. In Greco-Roman metrics and in the description of the metrics of other literatures, the macron was introduced and is still widely used in dictionaries and educational materials to mark a long (heavy) syllable. Even relatively recent classical Greek and Latin dictionaries are still concerned with indicating only the length (weight) of syllables; that is why most still do not indicate the length of vowels in syllables that are otherwise metrically determined. 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 following languages or transliteration systems use the macron to mark long vowels: Slavicists use the macron to indicate a non-tonic long vowel, or a non-tonic syllabic liquid, such as on l, lj, m, n, nj, and r. Languages with this feature include standard and dialect varieties of Serbo-Croatian, Slovene, and Bulgarian. Transcriptions of Arabic typically use macrons to indicate long vowels – ا (alif when pronounced /aː/), و (waw, when pronounced /uː/ or /oː/), and ي (ya', when pronounced /iː/ or /eː/). Thus the Arabic word ثلاثة (three) is transliterated thalāthah. Transcriptions of Sanskrit typically use a macron over ā, ī, ū, ṝ, and ḹ in order to mark a long vowel (e and o are always long and consequently do not need any macron). In Latin, many of the more recent dictionaries and learning materials use the macron as the modern equivalent of the ancient Roman apex to mark long vowels.