Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
addŭbĭtātĭo, ōnis, f. [addubito], a doubting, a rhetor. fig., Mart. Cap. 5, p. 171; Cic. Off. 3, 4, 18, where dubitatio is the better reading (B. and K.).