atlacomolli.

Headword: 
atlacomolli.
Principal English Translation: 

a well (a source of water), or a valley with water (see Karttunen)
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), 211.

IPAspelling: 
ɑːtɬɑkomoːlli
Alonso de Molina: 

atlacomulli. pozo.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 8r. col. 1. Thanks to Joe Campbell for providing the transcription.

abarrancadero assi. atlacomulli. acuezcomatl.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1555, part 1, Spanish to Nahuatl, f. 1r.

Frances Karttunen: 

ĀTLACOMŌL-LI well, valley with water / pozo (M), valle (con agua) (Z)[(1)Zp.142]. Z has E for A in the second syllable. See Ā-TL, TLACOMŌL-LI.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 13.

Lockhart’s Nahuatl as Written: 

atl, tlacomolli; large hole or depression
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), 211.