Definition from Wiktionary, the free dictionary
saltillo (plural saltillos)
- In Mexican languages, especially Nahuatl, a glottal stop or fricative sound.
- An apostrophe-like symbol (Ꞌ or ꞌ) used to represent this sound.
- 1915: Nahuatl ’ (saltillo) can be clearly shown to be developed in certain cases from syllabically final -t or -k, ... —Southern Paiute and Nahuatl - A Study in Utoaztekan, Part II, Edward Sapir, American Anthropologist, New Series, Vol. 17, No. 2 (Apr.-Jun., 1915)
- 1937: In Aztec the second ultra-short vowel is syncopated, leaving however the glottal consonant or “saltillo,” ... —The Origin of Aztec Tl, B.L. Whorf, American Anthropologist, New Series, Vol. 39, No. 2 (Apr.-Jun., 1937)
- 1960: ... the grave accent for the saltillo, as in tàtli /taˀλi/ father; and the circumflex for the ‘saltillo final’, as in tātlî /ta·λiˀ/ we drink. ... The saltillo of Rincón corresponds to that of Carochi, with the additional information from Rincón that the saltillo ‘solamente se halla en la sílaba breve’. —'Accent' in Classical Aztec, William Bright, International Journal of American Linguistics, Vol. 26, No. 1. (Jan. 1960)
- 1993: Third, Whorf’s hypotheses concerning the origin of “saltillo” (basically glottal stop) are an important stage in the development of Uto-Aztecan linguistics, and in the study of Nahuatl in particular. —Pitch Tone and the "Saltillo" in Modern and Ancient Nahuatl, Lyle Campbell and Frances Karttunen, International Journal of American Linguistics, Vol. 59, No. 2 (Apr., 1993)
- 2005?: The famous "saltillo" is a glottal stop [ʔ] in some variants, or a fricative [h] in others, but there are not two separate glottal phonemes. —Nahuatl Consonants, David Tuggy 
saltillo m (plural saltillos)