cuapitzahuac.

Headword: 
cuapitzahuac.
Principal English Translation: 

a triangular shape narrow at the top and wide at the bottom (see Molina)

Orthographic Variants: 
quapitzauac, quapitzahuac
Alonso de Molina: 

quapitzauac. figura ahusada hazia arriba, y ancho en lo baxo.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 85r. col. 2. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

iuhquj in tlemjiaoatl, iuhqujn tlecueçallotl, iuhqujn ilhuqujn tlaujzcalli pipixauhticaca, injc neçia iuhqujn ilhujcatl qujçoticac, tzimpatlaoac, quapitzaoac = like a flame, a tongue of fire, as if it were showering the light of the dawn. It appeared as if it were piercing the heavens; it was wide at the base and pointed at the top. (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 8 -- Kings and Lords, no. 14, Part IX, 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, 1951), 17.