◌̄ character spelling unconfirmed
Definitions
  1. A diacritical mark of the Latin script, called àmì ohùn àárín (“middle-tone mark”) in Yoruba, and found on Ā/ā, Ē/ē, Ẹ̄/ẹ̄, Ī/ī, Ō/ō, Ọ̄/ọ̄, Ū/ū, N̄/n̄ and M̄/m̄. Used to indicate middle-tone, omitted on vowels but marked on syllabic nasals to avoid conflation with nasal vowels diacritic
Source: Wiktionary, where this word is spelled “◌̄”. Reference: en-◌̄-yo-character-lX-3oAy6