mora

noun

mo·​ra ˈmȯr-ə 

plural morae ˈmȯr-(ˌ)ē 

-ˌī

or moras

: the minimal unit of measure in quantitative verse equivalent to the time of an average short syllable

Word History

Etymology

Latin, delay; akin to Old Irish maraid it lasts

First Known Use

1832, in the meaning defined above