ẹ̀ẹ̀- prefix /ɛ̀ɛ̀/
ẹ̀rẹ̀- (alternative)
Definitions
  1. adverbial prefix that denotes the number of times of an action or event morpheme
    ẹẹ- + méjì (“two”) → ẹ̀ẹ̀mejì (“twice (two times)”)
    ẹẹ- + mẹ́ta (“three”) → ẹ̀ẹ̀mẹta (“thrice (three times)”)
    ẹẹ- + ìmíì (“other”) → ẹ̀ẹ̀míì (“another time”)
    ẹẹ- + kẹta (“third”) → ẹ̀ẹ̀kẹta (“third time”)
    ẹẹ- + kọ̀ọ̀kan (“each one”) → ẹ̀ẹ̀kọ̀ọ̀kan (“occasionally”)
Etymology
Probably a contraction of ẹ̀rẹ̀- or contraction of ẹ̀rìn-.
Source: Wiktionary, where this word is spelled “ẹẹ-”. Reference: en-ẹẹ--yo-prefix-~-mGeLnN