tetzahua.

Headword: 
tetzahua.
Principal English Translation: 

to condense, thicken, or become solid; or, to thicken something (see Molina and Karttunen); or, to become firm (see Sahagún)

Orthographic Variants: 
tetzaua
IPAspelling: 
tetsɑːwɑ
Alonso de Molina: 

tetzaua. pararse espesso el betun, o el almendrada, o quajarse.
tetzaua. nitla. (pret. onitlatetzauh.) espessar, o quajar algo.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 111r. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

TETZĀHU(A) vt to condense, thicken, solidify something / espesar o cuajar algo (M), lo hace espeso, lo espesa, lo condensa (T) [(3)Tp.205,(3)Zp.32,56,197]. M also has intransitive tetzaua 'to condense, thicken, congeal,’ the preterit of which is formed by adding -C.

TETZĀHUALŌ nonact. TETZĀHU(A).
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 236.

Attestations from sources in English: 

tetzapa = it becomes firm (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), 97.