Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
pammachum (-chium), i, n., = παμμάχιον, an athletic contest, consisting of wrestling, boxing with the naked fists, and boxing with the cestus: in quibus (ludis) contendit pammachum (al. pammacho) quod nos pancratium vocamus, Hyg. Fab. 273; Inscr. Fabr. p. 106, n. 226.