tlacoyehua.

Headword: 
tlacoyehua.
Principal English Translation: 

the second son or daughter (see Molina); the middle child

Orthographic Variants: 
tlacoyeua, tlacoiehoa, tlacoieoa
IPAspelling: 
tɬɑhkojeːwɑ
Alonso de Molina: 

tlacoyeua. el segundo hijo o hija, o de tres o quatro engendrados o nacidos.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 118v. col. 1. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

This is also a common name in Morelos.
See Estudios de Cultura Náhuatl, no. 37.

Auh ca iz tica in titeach in tiacapãtli, auh ca iz tõca in titlacoieoa, auh in titlatoqujlia; auh iz tica ompa tica on in tixocoiutl = And here standest thou who art the oldest, the firstborn; and here art thou who art the second; and thou who followest; and thou who standest, who standest there, thou who art the youngest (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 87.

in cioatzintli, in at amotlacoieoauh, in at amotiacapan, in at noҫo amoxocoiouh = the little woman who is perhaps your second child, perhaps your eldest, or perhaps your youngest (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 153.