tlancuaitl.

Headword: 
tlancuaitl.
Principal English Translation: 

the knee (see Molina)

Orthographic Variants: 
tlanquaitl
Alonso de Molina: 

tlanquaitl. la rodilla dela pierna.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 129r. col. 2. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

Ҫaҫan tleino, ixtexolochtzitzin qujn topeuhtiuh. Totlanqua = What is that which has a small, wrinkled face, then goes kicking? Our knee (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 238.

Attestations from sources in Spanish: 

Ҫaҫan tleino, ixtexolochtzitzin qujn topeuhtiuh. Totlanqua = Que cosa y cosa, va dando embiones co cara arrogadas. Es las rodillas (centro de Mexico, s. XVI)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 238.