ilihuiz.

iliuiz. sin consideracion ydesuariadamente.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 37v. col. 1. Thanks to Joe Campbell for providing the transcription.

ĪLIHUIZ inconsiderately / sin consideración y desvariadamente (M), fuerte, fuertemente (Z) C marks the initial vowel long in only two of fourteen attestations; in the others it is unmarked for length. Z has E for I in the initial syllable and does not mark it long but consistently marks the vowel of the final syllable long. This is synonymous with TLALHUIZ and after forms the phrase ZAN ĪLIHUIZ with the same sense. This may be related to an intensifier in T, the canonical form which would probably be LALEHUIZ.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 104.

ilihuiz = thoughtlessly
Horacio Carochi, S.J., Grammar of the Mexican language with an explanation of its adverbs (1645), translated and edited with commentary by James Lockhart, UCLA Latin American Studies Volume 89 (Stanford: Stanford University Press, UCLA Latin American Center Publications, 2001), 503, and see 232–33, 402–03; main discussion, 414–15 (with n9)