fingernail(s), toenail(s) (see Molina and Karttunen) (we also have an entry for iztetl, which is a variant spelling); this nail can also pertain to an animal, as the glyph for Iztitlan appears to have the claw of an eagle, or other animal
See an image that represents iztitl in the Visual Lexicon of Aztec Hieroglyphs, ed. Stephanie Wood (Eugene, Ore.: Wired Humanities, 2020-present).
tzontli, itztitl = the hair, the fingernail (a metaphor for a relative, a descendant, a newborn male child) (central Mexico, sixteenth century)
tzontle, iztitle: oticmjhijovilti, oticmociavilti: otijoculoc in vmeiocan in chicunauhnepanjuhca = O hair, O fingernail, thou hast endured fatigue, thou hast endured weariness; thou wert formed in the place of duality, [which is above] the nine heavens in tiers (central Mexico, sixteenth century)
tzontle, iztitle = O hair, o fingernail (central Mexico, sixteenth century)
in mach vel iehoantin in tzoneque, in jzteque in totecujiooan = it seemeth that verily these same who are possessors of hair, who are possessors of fingernails, are our lords (central Mexico, sixteenth century)
tozti or tizti = (our) fingernails
iztitl = finger nail
ca omitl = it is bone
tetzaoac = hard
oapaoac = firm
chicaoac = strong
tetzcaltic = smoth
patzaoac = depressed
tlatataca = it scratches
ic netataco = with it there is scratching
ic nemomotzolo = with it there is clawing (central Mexico, sixteenth century)
itztitl = fingernail(s), toenail(s) (central Mexico, sixteenth century)
achtopa atotoniltica anquixamizque anquicamapacazque, anquitequilizque in izti = primero le lauen la cara y las manos y la boca con agua caliente y cortalle las uñas (centro de Mexico, s. XVII)