Principal English Translation: 

a line, stripe, streak, ray, dash, scratch, or mark (literally, black stick) (see Molina)

Orthographic Variants: 
tlilquauitl, tlilquahuitl
Alonso de Molina: 

tlilquauitl. raya.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 148r. col. 1. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

tlilquahuitl = blackish purple
William Gates, An Aztec Herbal: The Classic Codex of 1552 (2012).

Attestations from sources in Spanish: 

la línea ó trazo se dice tlilquauitl (palo [palote] negro)