patzihui.

Principal English Translation: 

for something to get crushed, bruised, dented in, or for a swelling to subside (see Karttunen and Molina); also, for something to soften (see attestations)

Orthographic Variants: 
patziui
IPAspelling: 
pɑːtsiwi
Alonso de Molina: 

patziui. (pret. opatziuh.) abollarse alguna cosa, o deshincharse el encordio. &c.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 80v. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

PĀTZIHU(I) for something to get crushed, bruised, dented in, or for a swelling to subside / abollarse alguna cosa o deshincharse el encordio (M) [(1)Tp.176]. See PĀTZOĀ.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 190.

Attestations from sources in English: 

patziui = it softens (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 10 -- The People, No. 14, Part 11, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 106.