xaxamatza.

Headword: 
xaxamatza.
Principal English Translation: 

to break certain brittle things into pieces; to rout one's enemies, inflicting great casualties (see Karttunen and Molina)

IPAspelling: 
ʃɑʃɑmɑtsɑ
Alonso de Molina: 

xaxamatza. nite. (pret. onitexaxamatz.) hazer pedazos alos enemigos, haziendo gran estrago enellos.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 158v. col. 2. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

XAXAMATZ(A) vt to break certain brittle things into pieces; to rout one’s enemies, inflicting great casualties / quebrar y hacer pedazos estas cosas (huevos, tecomates, guitarras, etc.) (C), hacer pedazos a los enemigos, haciendo gran estrago en ellos (M) [(3)Cf.75r]. See XAMĀN(I), XAXAMACA.

XAXAMACHILIĀ applic. XAXAMATZ(A).
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 322.

Attestations from sources in English: 

xaxamatza (verb) = to cut in pieces, to break into bits
Daniel Garrison Brinton, Ancient Nahuatl Poetry: Containing the Nahuatl Text of XXVII Ancient Mexican Poems (1877), 167.