something very green and fresh; or, one who is pale from fear or from sickness (see Molina)
Alonso de Molina:
xiuhcaltic. cosa muy verde y fresca, o descolorido de miedo o de enfermedad. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 159v. col. 2. Thanks to Joe Campbell for providing the transcription.