quimichin.

Headword: 
quimichin.
Principal English Translation: 

a mouse, a rodent (see Molina); also: small, dwarf, or baby (see Karttunen)

IPAspelling: 
kimitʃ
Alonso de Molina: 

quimichin. raton.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 90r. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

QUIMICH-IN pl: QUIMICHTIN ~ QUIQUIMICHTIN ~ QUIMICHI-MEH mouse / ratón (M) The alternate plural QUIMICHIMEH from M is the standard one for X and is built on MICHIN as a unitary stem rather than stem plus -IN absolutive suffix. It probably represents QUIMICHIMMEH with nasal assimilation and reduction of the resulting geminate consonant. QUIMICH-IN is used as a diminutive meaning 'small, dwarf, baby,’ as in Z with the local word for opossum to mean 'baby opossum.'
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 211.

Attestations from sources in English: 

See an image that represents quimichin in the Visual Lexicon of Aztec Hieroglyphs, ed. Stephanie Wood (Eugene, Ore.: Wired Humanities, 2020-present).

"1525 .... nican ypan xihuitl tlaquimicchqualoc [....] (p. 805)" = "1525 .... In this year things were eaten by mice [....]." (Anales de Puebla y Tlaxcala, no. 2, 1524–1674)
Frances Krug, "The Nahuatl Annals of the Tlaxcala-Puebla Region," ch. 3, p. 42, Ph.D. Dissertation draft written in the 1980s, with transcriptions and translations approved by James Lockhart. Cited here by SW.

1548 Nican ypan xihuitl yn huel otlaquimichcualoc = 1548 Here in this year things were really eaten up by mice.
Here in This Year: Seventeenth-Century Nahuatl Annals of the Tlaxcala-Puebla Valley, ed. and transl. Camilla Townsend, with an essay by James Lockhart (Stanford: Stanford University Press, 2010), 72–73.

Quimich = Mouse, a name given to a child
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 254.

Ma quimichpil oconatlic. Iquac mitoa: intla itla oticpeoaltica, auh zan no onitlacauh = Possibly a mouse drank it. This is said when we are fighting for something and giving up.
Thelma D. Sullivan, "Nahuatl Proverbs, Conundrums, and Metaphors, Collected by Sahagún," Estudios de Cultura Náhuatl 4 (1963), 112–113.

themes: 
Animals, Bugs, Insects, Reptiles, Fish, etc.