ixtlamati.

Headword: 
ixtlamati.
Principal English Translation: 

(noun) a wise person, one who uses reason and has experience (see Molina); or (verb), to exercise reason and prudence and to make gestures with one's hands and face (see Karttunen and Molina); or (adjective), prudent, experienced
For the latter, see: The Tlaxcalan Actas: A Compendium of the Records of the Cabildo of Tlaxcala (1545-1627), eds. James Lockhart, Frances Berdan, and Arthur J.O. Anderson (Salt Lake City: University of Utah Press, 1986), 105.

IPAspelling: 
iːʃtɬɑmɑti
Alonso de Molina: 

ixtlamati. sabio que vsa de razon y es esperimentado.
ixtlamati. n. (pret. onixtlamat.) ser experimentado vsar de razon y prudencia, o hazer gestos y visajes
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 48r. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

ĪXTLAMAT(I) pret: ĪXTLAMAT to exercise reason and prudence, to make gestures with one’s hands and face, to be familiar with a place / ser experimentado usar de razón y prudencia, o hacer gestos y visajes (M), conoce (un lugar) (T) There are two distinct senses of ĪXTLAMAT(I). One literally has to do with the surface appearance of something conveying information, while the other involves the lexicalized sense of ‘prudence.’ See ĪX-TLI, MAT(I). ĪXTLAMATĪHUA nonact. ĪXTLAMAT(I) ĪXTLAMACHĪTIA caus. ĪXTLAMAT(I)
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 121.

Attestations from sources in English: 

In Tlaxcalan usage, this came to mean "established," or in effect "wealthy."

In Culhuacan, we see it to mean "to be acquainted with" (familiar with) something.

Can mean: "they are experienced."

auh amo cenca nixtlamati yn onpa mani huehuetlalli = I am not well acquainted with where the patrimonial lands are there. (Culhuacan, 1580)
Testaments of Culhuacan (provisionally modified first edition), eds. Sarah Cline and Miguel León-Portilla, online version http://www.history.ucsb.edu/cline/testaments_of_culhuacan.pdf, 10.

Xomolli, tlayoualli ticmotoctia. Inin tlatolli, itechpa mitoaya: in iquac aca ixtlamati, anozo mozcaliani, iximacho pilli, anozo tecutli: auh zatepan quipoloa in imauizyo. = You hide yourself in a corner, in the dark. This was said when some able person, perhaps an experienced and renowned noble or official, lost his good name.
Thelma D. Sullivan, "Nahuatl Proverbs, Conundrums, and Metaphors, Collected by Sahagún," Estudios de Cultura Náhuatl 4 (1963), 176–177.

in jquac ie ixtlamatia = when they had already reached the age of discretion (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), 93.

in quenjn tenanoan, tetaoan, qujnnetoltiaia in oqujchpipiltotonti, in cioapipiltotonti: injc calmecac nemjzque, in jquac ie qualtoton, in ie achi ixtlamati = how the mothers [and] the fathers promised that the boys [and] the girls would live in the calmecac when they were already partly grown, already somewhat experienced (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), 209.

nixtlamati = I am wise (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 10 -- The People, No. 14, Part 11, 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), 112.

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