Irish tosach

← Proto-Celtic *towissākos (inherited)

← Irish taoiseach (mention)

← Scottish Gaelic toiseach (cognate)

← Scottish Gaelic tòisich (mention)

← Proto-Indo-European *wedʰ- (derived)

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

← Old Irish tosach (inherited)

→ Irish tosaigh (link)

→ Irish tosaí (mention)

→ Irish leatosach (prefix)

→ Irish lántosach (affix)

→ Irish urthosach (prefix)