A short, straight, horizontal mark [-], placed over vowels to denote that they are to be pronounced with a long sound; as, a, in dame; e, in seam, etc.

A short, straight mark placed horizontally over a vowel to indicate it has the long sound.

a mark placed over a long vowel to mark quantity

a diacritical mark (-) placed above a vowel to indicate a long sound

a horizontal line over a vowel

a "mark placed over a vowel to indicate that the vowel is long" (Webster)

a straight line or bar used above a vowel in the phonetic guide to a word to indicate a long sound

A mark often used to show a long vowel sound e.g.

In prosody, a macron is the mark placed over a syllable in a line of verse to show that it is stressed. It is denoted by the following symbol (−). See also breve and meter.

A macron, from Greek (makros) meaning "large", is a diacritic ¯ placed over a vowel originally to indicate that the vowel is long. The opposite is a breve ˘, used to indicate a short vowel. These distinctions are usually phonemic.