Old Irish ard

← Proto-Celtic *ardwos (inherited)

← Welsh ardd (cognate)

← Proto-Indo-European *h₃erdʰ- (root)

← Proto-Indo-European *h₃erdʰwós (inherited)

← Proto-Indo-European *h₃erdʰ- (mention)

← Latin arduus (cognate)

→ Irish ard (inherited)

→ Irish ardaigh (mention)

→ Scottish Gaelic àrd (inherited)

→ Manx ard (inherited)

→ Latin arduus (cognate)

→ Old Irish Ard Machae (compound)