papaqui.

Headword: 
papaqui.
Principal English Translation: 

to rejoice, celebrate, have fun (see Lockhart), to enjoy oneself, to take great pleasure (see Karttunen and Molina)

IPAspelling: 
pɑhpɑːki
Alonso de Molina: 

papaqui. ni. (pret. onipapac.) tomar plazer y alegrarse.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 79v. col. 2. Thanks to Joe Campbell for providing the transcription.

papaqui. nic. (pret. onicpapac.) fruir o gozar de algo muchas vezes.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 79v. col. 2. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

PAHPĀQU(I) to enjoy oneself, to take great pleasure / tomar placer y alegrarse (M) M also has transitive papaqui 'to repeatedly enjoy something' R consistently has PAHPAHQU(I) for PAHPĀQU(I) and its derivations. redup. PĀQU(I). PAHPĀCOHUA nonact. PAHPĀQU(I).
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 184.

Lockhart’s Nahuatl as Written: 

ni. to rejoice, celebrate, have fun. Class 2: ōnipahpac. distributive/frequentative of pāqui. 229
James Lockhart, Nahuatl as Written: Lessons in Older Written Nahuatl, with Copious Examples and Texts (Stanford: Stanford University Press and UCLA Latin American Studies, 2001), 229.

Attestations from sources in English: 

cenyohual in papacohuac quahoocotl in tlatlac yn icpac teocalli = all night people celebrated, torches were burned on top of the church (early seventeenth century, central New Spain)
Annals of His Time: Don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, James Lockhart, Susan Schroeder, and Doris Namala, eds. and transl. (Stanford: Stanford University Press, 2006), 48–49.

mochtin papaqui cuica mamatlapalçŏçoa. niman ye peua in patlanizue = they all rejoice, they sing, they spread their wings. Then they begin to fly (late sixteenth century, Central Mexico)
Louise M. Burkhart, Before Guadalupe: The Virgin Mary in Early Colonial Nahuatl Literature, Institute for Mesoamerican Studies Monograph 13 (Albany: University at Albany, 2001), 27.

xipapaqui, ximotlamachti = be happy, be joyous
John F. Schwaller, "The Pre-Hispanic Poetics of Sahagún's Psalmodia christiana," in Psalms in the Early Modern World, eds. Linda Phyllis Austern, Kari Boyd McBride, and David L. Orvis (London: Ashgate, 2011), 330.

themes: 
Emotions