nelhuayotl.

Headword: 
nelhuayotl.
Principal English Translation: 

a beginning, foundation, or starting point; a root or vein (see Molina and Karttunen)

IPAspelling: 
nelwɑyoːtɬ
Alonso de Molina: 

nelhuayotl. principio, fundamento, o comienzo.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 66v. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

NELHUAYŌ-TL pl: -MEH base, foundation, starting point, root or vein / principio, fundamento, o comienzo (M), raíz (T), vena (X) [(3)Tp.132,154,167,(3)Xp.56]. This is an abstract derivation from NELHUA-TL 'root,' but apparently it can be used concretely and hence synonymously with NELHUA-TL itself. It is not clear whether the possessed form attested in T is the simple possessed form of this or the inalienably possessed form of NELHUA-TL. M also has nelhuayo, which represents NELHUAYOH 'something that has a root,' which also appears in P.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 164.

Attestations from sources in English: 

nelhuayotl (noun) = a root; fig., principle, foundation, essence
Daniel Garrison Brinton, Ancient Nahuatl Poetry: Containing the Nahuatl Text of XXVII Ancient Mexican Poems (1877), 158.