[ dʌɪ'mi:trədɒn ]
■ noun a large fossil carnivorous mammal-like reptile of the Permian period, with long spines on its back supporting a sail-like crest.
Origin
mod. L., from di- 'twice' + Gk metron 'measure' + odous , odont- 'tooth' (taken in the sense 'two long teeth').