Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
actŭārĭŏlum, i, n. dim. [actuarius], a small, swift vessel impelled by oars, row-boat, barge, Cic. Att. 10, 11, 4; 16, 3, 6; 16, 6, 1.