tlacacco.

Headword: 
tlacacco.
Principal English Translation: 

tranquilly, slowly, peacefully; with caution, discretion; sweetly, gently

Orthographic Variants: 
tlacaco
IPAspelling: 
tɬɑːkɑkko
Alonso de Molina: 

tlacaco. segura y pacificamente, o sin zozobras.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 115r. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

TLĀCACCO peacefully, with tranquility / segura y pacificamente, o sin sobras (M) [(2)Cf.120r]. C attests this with germinate CC, while M has a single consonant. See CACTI.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 251.

Horacio Carochi / English: 

tlācacco = peacefully, calmly, etc.
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), 513.