-teiccauh.

Headword: 
-teiccauh.
Principal English Translation: 

younger sibling of a male, younger brother

Caterina Pizzigoni, ed., Testaments of Toluca (Stanford: Stanford University Press and UCLA Latin American Center Publications, 2007), 44.

Orthographic Variants: 
-teicauh, -tejcauh
Lockhart’s Nahuatl as Written: 

more common form of -iccāuh, double possessed.
James Lockhart, Nahuatl as Written: Lessons in Older Written Nahuatl, with Copious Examples and Texts (Stanford: Stanford University Press and UCLA Latin American Studies, 2001), 233.

Attestations from sources in English: 

yz ca oc ce vecapa ycauh y yaotl ytoca ytoca [sic] nacxitl- ça ycnovquichtl- onmoçivauhtica ya matlacpovally y mic yçivauh = Here is in addition the distant younger sibling [i.e. cousin] of Yaotl, named Nacxitl. He is just a widower. He had married; 200 days ago his wife died. (Cuernavaca region, ca. 1540s)
The Book of Tributes: Early Sixteenth-Century Nahuatl Censuses from Morelos, ed. and transl. S. L. Cline, (Los Angeles: UCLA Latin American Center Publications, 1993), 170–173.

y cuauhtliztac hocate ycava- yeyti = Quauhtliztac has three younger siblings. (Cuernavaca region, ca. 1540s)
The Book of Tributes: Early Sixteenth-Century Nahuatl Censuses from Morelos, ed. and transl. S. L. Cline, (Los Angeles: UCLA Latin American Center Publications, 1993), 164–165.

yz cate ycava onmeti = Here are his two younger siblings. (Cuernavaca region, ca. 1540s)
The Book of Tributes: Early Sixteenth-Century Nahuatl Censuses from Morelos, ed. and transl. S. L. Cline, (Los Angeles: UCLA Latin American Center Publications, 1993), 164–165.

yteicauh, ytejcauh = his younger brother (Tepetlaoztoc, sixteenth century)
Barbara J. Williams and H. R. Harvey, The Códice de Santa María Asunción: Facsimile and Commentary: Households and Lands in Sixteenth-Century Tepetlaoztoc (Salt Lake City: University of Utah Press, 1997), 76.