like "ouch" -- the sound someone makes when complaining about being hurt (an onomatopoetic word)
Orthographic Variants:
ahqua
Alonso de Molina:
ahqua. ay ay. del que se quexa delo que le duele. interiection. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 3r. col. 1. Thanks to Joe Campbell for providing the transcription.