Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
cŏ-ădūno, āvi, ātum, 1, v. a., to unite, add, or join together, to collect into one (postclass.), Dig. 10, 4, 7; 2, 14, 9; Aur. Vict. Vit. 1; Dict. Cret. 4, 13.