tetl.

Headword: 
tetl.
Principal English Translation: 

stone; also a counter, a way of representing numbers, but referring to things that are round (see Molina, note from 1555)

IPAspelling: 
tetɬ
Alonso de Molina: 

tetl. piedra, generalmente.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 107v. col. 2. Thanks to Joe Campbell for providing the transcription.

NOTE: Molina, in the 1555 edition of his vocabulario, notes a difference between cecentetl and cecen. The first means "a cada cosa redonda," and the second means "a cada cosa no redonda." The implication is that the "tetl" addition suggests something round, like a stone, and not just a counter/unit. See f. 2v.

Frances Karttunen: 

TE-TL possessed form: -TEUH stone / piedra generalmente (M) By extensión this can mean 'gem' or 'ornament' and in another direction, any solid discrete object. TŌTOLTE-TL 'egg' is literally 'bird-stone’, and it is often shortened to TE-TL. ĀTE-TL 'testicle' is literally 'water-stone.' TE-TL is used as a numeral classifier in counting small objects, CENTE-TL 'one'< CEM, ŌNTE-TL 'two'< ŌME, etc. It also often compounds with the names of body parts with no apparent change of meaning as in QUECH-TLI ~ QUECHTE-TL 'neck.'
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 235.

Lockhart’s Nahuatl as Written: 

stone; counter for hard objects and many other things. tetl quahuitl, punishment or disease.
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), 234.

Attestations from sources in English: 

Tlen in hueli in tetotontin? Cuix tlacaqui? Cuix yolizmati? Amo zan tetl texcali ycocopalo, yocotzoyo = What power do miserable little rocks have? Do they have understanding? Are they prudent, wise and creative? No—just the excretions of rocks and volcanic outcroppings.
Bartolomé de Alva, A Guide to Confession Large and Small in the Mexican Language, 1634, eds. Barry D. Sell and John Frederick Schwaller, with Lu Ann Homza (Norman: University of Oklahoma Press, 1999), 77.

tetl quahuitl, "stone(s) + stick(s) = punishment;"
See Sell's comments in Bartolomé de Alva, A Guide to Confession Large and Small in the Mexican Language, 1634, eds. Barry D. Sell and John Frederick Schwaller, with Lu Ann Homza (Norman: University of Oklahoma Press, 1999), 22.

cequi ntí n ycatematl, tetl quitlaza ya = Cequi:ntin i:ca tematl tetl quitla:zaya = Some threw down rocks with slings
Anónimo mexicano, ed. Richley H. Crapo and Bonnie Glass-Coffin (Logan, UT: Utah State University Press, 2005), 39.

Ioan monequi ytech pohuizque matlactli tlaxinque no matlactli tetçotçonque = And it is required that ten carpenters be attached to him, and also ten stonemasons (Coyoacan, mid-sixteenth century)
Beyond the Codices, eds. Arthur J.O. Anderson, Frances Berdan, and James Lockhart (Los Angeles: UCLA Latin American Center, 1976), Doc. 26, 150–151.

tliltic teçontli, in chichiltic teçontli, yn iztac tetl yn mvteneva texamitl = black pumice stone, red pumice stone, white stones called stone adobes (central Mexico, sixteenth century)
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 226.

We sometimes see stones thrown as a part of land possession activities. See an example below, in attestations from manuscripts translated into Spanish. Search also poseción. (SW)

The Florentine Codex, especially Book 6, refers to the pairing of tetl and quahuitl (the rocks, the wood) in association with knowing secret things, perhaps such as the wonders of nature. But it also relates to an ability to see into or through things. (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), see, for example, 49, 70.

ca oticmononochili in quavitl, in tetl itic tlamati, tlachia = for thou hast consulted the one who knoweth, who seeth things [within] wood, within stones (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), 31.

tetl itic, quavitl itic tlamati, tlachia tlacaquj in totecujo: mjtztlamachiliz ҫã cuel itla mopan qujoalmonequjltiz = our lord knoweth, seeth, heareth the things within the rocks, within the wood. He will know thy secrets (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), 49.

A ca ie, moietztica, in tlacatl, in totecujo: in tetl, in quavitl itic tlachia, in tehitic tlachia, in tehitic tlamati = The master, our lord, is already present. He seeth within the rocks, [within] the wood; he seeth within one; he knoweth of things within one (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), 70.

Attestations from sources in Spanish: 

Tlen in hueli in tetotontin? Cuix tlacaqui? Cuix yolizmati? Amo zan tetl texcali ycocopalo, yocotzoyo = Pues que poder tienen essas pedresuelas? Por ventura tienen entendimiento, ò discurso? No por cierto, porque son vnas gomas de los riscos y peñascos.
Bartolomé de Alva, A Guide to Confession Large and Small in the Mexican Language, 1634, eds. Barry D. Sell and John Frederick Schwaller, with Lu Ann Homza (Norman: University of Oklahoma Press, 1999), 76–77.

tza cetetl yn icac yn calli yhua yn ixquich yn oca tepeuhtonc yn ixquich ytetl mochi = no hay más de una casa y todos aquellos montones de piedras que hay (San Juan Teotihuacan, 1563)
Vidas y bienes olvidados: Testamentos indígenas novohispanos, vol. 2, Testamentos en náhuatl y castellano del siglo XVI, eds., Teresa Rojas Rabiela, Elsa Leticia Rea López, Constantino Medina Lima (Mexico: Consejo Nacional de Ciencias Tecnología, 1999), 138–139.

in tetl, in quahuitl = un metáforo que quiere decir el castigo (literalmente, la piedra, el palo)
Huehuehtlahtolli. Testimonios de la antigua palabra, ed. Librado Silva Galeana y un estudio introductorio por Miguel León-Portilla (México: Secretaría de Educación Pública, Fondo de Cultura Económica, 1991), 54–55.

ynic otetl = segunda [tierra] (con otra ortografía: inic ontetl)
ynic quetetl = tercera [tierra] (o: inic eytetl)
ynic nauhca = cuarta
(son ejemplos del uso de la palabra para contar cosas; Ocotelulco, 1619)
Vidas y bienes olvidados: Testamentos indígenas novohispanos, vol. 1, Testamentos en castellano del siglo XVI y en náhuatl y castellano de Ocotelulco de los siglos XVI y XVII, eds. Teresa Rojas Rabiela, Elsa Leticia Rea López, y Constantino Medina Lima (Mexico: CIESAS, 1999), 188–191.

onenen yn ipan tlalli otlamomotlac yca tetl = se anduvo paseando por el suelo tirando piedras de una parte a otra (Ciudad de México, 1582)
Luis Reyes García, Eustaquio Celestino Solís, Armando Valencia Ríos, et al, Documentos nauas de la Ciudad de México del siglo XVI (México: Centro de Investigación y Estudios Superiores en Antropología Social y Archivo General de la Nación, 1996), 181.

tetl = piedra; noteuh = mi piedra
Rémi Siméon, Diccionario de la lengua náhuatl o mexicana (Mexico: Siglo XXI, 1988), xlii.

tetl indica objetos redondos, pulidos, como las piedras (tetl), los huevos, los frutos, etc.; centetl xochiqualli, un fruto; on tetl, dos, yetetl, tres; nauhtetl, cuatro; macuiltetl, cinco; chiquacentetl, seis, etc.
Rémi Siméon, Diccionario de la lengua náhuatl o mexicana (Mexico: Siglo XXI, 1988), xlvi.

Cuix ticneltoca ca in izquitetl sacrmento cenca techipauh cenca tequaltili = Crees que todos los Sacramentos de la Yglesia limpian y purifican el alma...? (centro de México, 1600)
Fray Juan Bautista, Advertencias para los confesores de los naturales (Primera Parte). Primeros Libros, http://www.primeroslibros.org.

themes: 
Metaphors, Proverbs, Riddles
Numbers, Math
Stones, Masonry