something thick or curdled, such as bitumen (see Molina)
IPAspelling:
tetsɑktik
Alonso de Molina:
tetzactic. cosa espessa o quajada, assi como betun o poleadas. &c. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 110v. col. 2. Thanks to Joe Campbell for providing the transcription.