- a diacritical mark (¯) placed over a letter, used in prosody, in the orthography of some languages, and in several types of phonetic respelling systems, to represent a long vowel
WordReference Random House Unabridged Dictionary of American English © 2015
Phoneticsa horizontal line used as a diacritic over a vowel to indicate that it has a long sound or other specified pronunciation, as (ā) in fate (fāt).
- noun, nominal use of Greek makrón, neuter of makrós long. See macro- 1850–55