Old Irish toísech

← Proto-Celtic *towissākos (inherited)

← Welsh tywysog (cognate)

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

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

← Primitive Irish ᚈᚑᚃᚔᚄᚐᚉᚔ (inherited)

→ English Macintosh (cognate)

→ English taoiseach (mention)

→ Irish Taoiseach (inherited)

→ Irish taoiseach (inherited)

→ Irish túisce (inherited)