Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dŭŏ-dē-vīginti, card. num., eighteen, Plaut. Poen. 4, 2, 74 sq.; Cic. Ac. 2, 41, 128; id. Rep. 2, 22; Caes. B. G. 2, 5 fin.; id. B. C. 3, 71 al.; cf. also: annis mille centum et duobus de viginti fere, etc., Eutr. 10, 9.