n. [ Maori tuatàra; tua on the farther side (the back) + tara spine. ] (Zool.) A large iguanalike reptile (Sphenodon punctatum) formerly common in New Zealand, but by 1900 confined to certain islets near the coast. It reaches a length of two and a half feet, is dark olive-green with small white or yellowish specks on the sides, and has yellow spines along the back, except on the neck. It is the only surviving member of the order