Principal English Translation:
to become night, to be night, to grow dark, for darkness to fall (see Lockhart, Karttunen, and attestations); see also yohualli
Alonso de Molina:
youa. (pret. oonyouac.) anochecer.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 41v. col. 1. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
YOHUA to get dark, for night to fall / anochecer (M). YOHUALTIĀ caus. YOHUA. YŌYOHUA redup. YOHUA.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 340.
Lockhart’s Nahuatl as Written:
To be or grow dark. Class 1: ōyohuac. see also tlayohua.
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), 242.
Attestations from sources in English:
in canjn impan iooatiuh vncan cochi, moztla ivi = Where night came upon them, there they slept. On the morrow, likewise (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), 175.
IDIEZ traduc. inglés:
1. root of TLAYOHUA, YOHUALLI and other words. to get dark or for night to fall. 2. raíz de YOHUALTIC, TZONYOHUALLI and other words. to go around in circles.
IDIEZ def. náhuatl:
Nouhquiya YAHUA. 1. TLAYOHUA, YOHUALLI huan cequinoc tlahtolli iyollo. 1. Cehui tlahuilli zo huetzi tonatiuh [Mc. 41v]. 2. YOHUALTIC, TZONYOHUALLI huan cequinoc tlahtolli iyollo. Malacachihui.