Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
praefractus, a, um, Part. and P. a., from praefringo.
prae-fringo, frēgi, fractum, 3, v. a. [frango], to break off before or at the end, to break to pieces, shiver (class.): ne caulis praefringatur, Cato, R. R. 33 (cited by Plin. 17, 22, 35, § 20): hastas, Liv. 8, 10; so, primam aciem telo, to break off the point of the missile, Just. 6, 8, 2: cornu galeae, Liv. 27, 33: praefracto rostro (triremis), Caes. B. C. 2, 6: praefracta strigilis, Lucil. ap. Gell. 3, 14, 10: praefracta ligna, Lucr. 1, 892.
Hence, praefractus, a, um, P. a.