Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ad-mordĕo, rsum, 2, v. a. (perf. admemordi, Plaut. Aul. Fragm. ap. Gell. 6, 9, 6), to bite at or gnaw, to bite into (cf. accīdo, to cut into).
* 2. admorsus, ūs, m. [admordeo], a biting at, a gnawing, a bite; trop.: vereor ne libellus iste admorsu duri dentis uratur, Symm. Ep. 1, 15.