a pan for washing something; soap, washcloth, or sink for washing crockery, dishes (see Molina)
IPAspelling:
tɬɑpɑːkoːni
Alonso de Molina:
tlapaconi. batan, lebrillo para lauar algo, xabon estropajo o fregadero de vaxilla. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 130v. col. 1. Thanks to Joe Campbell for providing the transcription.