macron
noun /ˈmækrɒn/
/ˈmeɪkrɑːn/
(linguistics- the mark (¯ ) that is placed over a vowel in some languages and in the International Phonetic Alphabet to show that the vowel is stressed or long
长音符；平调符 词源mid 19th cent.: from Greek makron, neuter of makros ‘long’.