tzintli (Mdz10v)
This element has been carved from the compound sign for the place name, Tenantzinco. In this representation of tzintli, a phonetic indicator and not literally meant to refer to the man's buttocks, we see about half a human body, largely naked. We know it is male because we see the white waistband of the loincloth. The body is upright and facing toward the viewer's left. The knees are up against the abdomen, making the bottom more prominent, but not particularly detailed, being in profile. On the other hand, there is a fair amount of detail in the legs and feet, showing some toes and a couple of white toenails.
Stephanie Wood
As with all—or at least the vast majority—of examples of this glyph, the meaning "buttocks" has nothing to do with the meaning of the glyphs, although it may have a metaphorical value of "lower." When modifying a place name, as Frances Karttunen suggests, the meaning of "tzin" is new, little, or lower. It can also refer to something revered, for instance, when combined with something having the element "teo" (from teotl, divine force).
c. 1541, but by 1553 at the latest
butts, buttocks, rear end, little, lower, bottom, nalgas, trasero
tzin(tli), buttocks, https://nahuatl.wired-humanities.org/content/tzintli
-tzin, new, little, lower, or reverential, https://nahuatl.wired-humanities.org/content/tzin
buttocks
Codex Mendoza, folio 10 verso, https://digital.bodleian.ox.ac.uk/objects/2fea788e-2aa2-4f08-b6d9-648c00..., image 31 of 188.
The Bodleian Libraries, University of Oxford, hold the original manuscript, the MS. Arch. Selden. A. 1. This image is published here under the UK Creative Commons, “Attribution-NonCommercial-ShareAlike 3.0 License” (CC-BY-NC-SA 3.0).