Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
cāsābundus (in the best MSS. cassāb-, on account of the first long a, like cassus, caussa, Juppiter, etc.), a, um, adj. [caso], ready to fall, tottering, Naev. ap. Varr. L. L. 7, § 53 Müll.; Macr. S. 5, 21, 16; cf. Paul. ex Fest. p. 48 Müll.