ollama.

Headword: 
ollama.
Principal English Translation: 

to play with a rubber ball using the buttocks (see Molina)

Orthographic Variants: 
utlama, ollamaliztli, ollamaniztli, ullamaliztli, ullama
IPAspelling: 
oːllɑmɑ
Alonso de Molina: 

ollama. n. (pret. onollan.) jugar ala pelota con las nalgas.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 76r. col. 1. Thanks to Joe Campbell for providing the transcription.
ullama. n. (pret. onullan.) jugar ala pelota con las caderas o nalgas.
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.

Attestations from sources in English: 

njman tlanaoatiaia, injc ollamaloz, injc teellaquaoaia, injc tepaqujltiaia tlatoanj: qujnnaoatiaia in calpixque, injc qujoalcujzque in olli, ioan nelpilonj, ioan queçeoatl, ioan maieoatl = then commanded that the ball game be played, in order to animate the people and divert them. He commanded that the majordomos to take out the rubber ball, and the girdles, and the leather hip guards, and the leather gloves (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), 58.

yntla utlama mitouaya ic quizcaltiaya in tonalli ic patia = If he played the rubber ball game, it was said that he thus nourished the day sign, that this is improved. (Central Mexico, sixteenth century)
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 162.

vllama, vncatca imolpixcaoa, ioan inmolancaoan, qujtlanjtoa in jxqujch tlaçotli = They played ball. There were his ball-catchers and his ball-players. They wagered [in this game] all [manner of] costly goods.
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), 29.

See also tlachtli.