◌̃ character spelling unconfirmed
Definitions
  1. A diacritical mark of the Latin script, called àmì fàágùn (“lengthend mark”). Formerly used to indicate any sequence of tones on extended vowels diacriticobsolete
Source: Wiktionary, where this word is spelled “◌̃”. Reference: en-◌̃-yo-character-pOMvtz-P