xopantla.

Headword: 
xopantla.
Principal English Translation: 

green time of the year, rainy season, summer (see Karttunen)

Orthographic Variants: 
xōpantlah
IPAspelling: 
ʃoːpɑntɬɑh
Alonso de Molina: 

xopantla. verano.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 161r. col. 2. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

XŌPANTLAH green time of the year, rainy season, summer / temporal, temporada, tiempo de las aguas, las aguas (T) [(1)Cf.88r, (1)Tp.248, (1)Xp.104]. X has -TLAN for –TLAH. See XŌPAN, -TLAH.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 331.