Principal English Translation: 

in the gully, in a dip in the terrain, perhaps also: in the middle

Orthographic Variants: 
tlacomulco, tlacōmolco
Attestations from sources in English: 

acā motlatique tlapechian, tlacomulco, anoço atlauhco, ie quimacacia ie quinmauhtia, in ma amo quimimachititi in iniauvan, in maca innemachpan inpā valcholoti = They did not hide anywhere on plains, in gullies, or in ravines, apprehensive and afraid lest their enemies spring upon them without warning, unawares. (Mexico City, sixteenth century)
James Lockhart, We People Here: Nahuatl Accounts of the Conquest of Mexico, Repertorium Columbianum v. 1 (Los Angeles: UCLA Center for Medieval and Renaissance Studies, 1993), 170.

IDIEZ traduc. inglés: 
terrain with a shallow depression.
IDIEZ def. náhuatl: 
Canahya campa eltoc oztoctic tlalli. “Martha ichan tlahuel tlacomolco huan yeca cequin macehualmeh axquinequih yazceh quipaxolotih.”
IDIEZ morfología: 
tla6, comōlli, co2.