Irish fáidh

← Proto-Celtic *wāti- (inherited)

← Proto-Indo-European *weh₂t- (root)

← Proto-Indo-European *wéh₂tis (inherited)

← Proto-Indo-European *weh₂t- (mention)

← Old Irish [[fáith]], [[fáid]] (inherited)

→ Irish banfháidh (affix)

→ Irish fáidhbhean (affix)

→ Irish fáidhiúil (affix)