'hadrosaur' originates from Greek, specifically the words 'hadros' and 'sauros', where 'hadros' meant 'thick' and 'sauros' meant 'lizard'.

'hadrosaur' entered scientific New Latin as the genus name 'Hadrosaurus' in the 19th century (from Greek roots), and the English common noun 'hadrosaur' was later adopted to refer to members of the family Hadrosauridae.

Initially it was a constructed scientific name meaning 'thick lizard'; over time it came to refer more broadly to 'duck-billed, herbivorous dinosaurs of the family Hadrosauridae'.