Principal English Translation:
who? or to whom? (see Molina), or, one who (see Karttunen)
Alonso de Molina:
aquin? quien, o a quien? preguntando.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 7v. col. 1. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
ĀQUIN (one) who; who? / ¿quién, o a quién? (M), alguien, quien, alguno (T) See ĀC.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 12.
Horacio Carochi / English:
āquin = who? (involves the combination of āc + in)
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), 70–73, 497.
Lockhart’s Nahuatl as Written:
āquin = who, interrogative; preceded by in, relative, or one who, whoever, etc. āc, in
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.
Attestations from sources in English:
Āquin tzàtzi? -- Ca yèhuātl in conētl. = Who's shouting? (It's) the child.
Āquìquê cuicâ? Who (which people, plural) are singing?
Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 37.
Āquìquê, or āquihqueh can also mean "those."
amo aqui, amo aquin = no one
Rebecca Horn's notecard file from Nahuatl study sessions with James Lockhart in the early 1980s.