The tortilla (frm the Spanish word “torta”) is used a a wrap for many Tex-Mex foods, such as burritos. The corn tortilla is the traditional one, but there are now flour and wheat tortillas as well.
 
   
The Tex-Mex Cookbook
by Robb Walsh
New York: Broadway Books
2004
Pg.115 (Glossary):
TORTILLAS
Corn tortillas are among the oldest foods in Mesoamerican culture. They are made of the corn dough called masa. Flour tortillas were invented in the Mexican state of Sonora, the nation’s largest wheat-producing region. Many grocery stores stock a wide variety of tortillas these days. There are plain and flavored flour tortillas, fluffy white corn tortillas, and old-fashioned corn tortillas. The old-fashioned corn ones, sometimes called enchilada tortillas, are somewhat leathery but hold up well in cooking. Use these for frying and save the flour tortillas and fluffy white corn tortillas for serving at the table.
 
Wikipedia: Tortilla
The Spanish word tortilla [torˈtiʝa] denotes two different classes of foods, depending on where the term is encountered. Etymologically, it is derived from the word torta, meaning a plain round cake.
(...)
But it is the Mexican meaning of “tortilla” that is most familiar to North Americans, and possibly most of the world outside of Europe and South America where the original Spanish meaning is best known.

In Mexican, Central American, American, and Canadian terms, a tortilla is a kind of thin, unleavened flat bread, made from finely ground maize (corn) or wheat flour. The maize version is the original North American tortilla and is regarded by many as the “authentic” tortilla. In fact, this form of bread pre-dates the arrival of Europeans to America, and was only called “tortilla” by the Spanish from its resemblance to the traditional Spanish round unleavened cakes and omelettes (originally made without potatoes, which are native to South America).

The flour tortilla is probably best known in the USA as the tortilla used to make burritos, a preparation originating in northern Mexico. Wheat tortillas are also a traditional staple of the peoples of northwestern Mexican states (such as Sonora and Chihuahua) and many southwestern US Native American tribes.

(Oxford English Dictionary)
tortilla
[Sp. dim. of torta cake: see TORTA.] 
In Mexico, A thin round cake made of maize-flour, baked on a flat plate of iron, earthenware, etc. and eaten hot.
1699 W. DAMPIER Voy. II. II. 43 Tartilloes are small Cakes made of the Flower of Indian Corn.
1828 LYON Mexico x. II. 142 Obliged to seek..for some woman, who will make a few tortillas or a dish of black beans.
1842 New World 11 June 373/3 Maiz..is chiefly used in the Tortillia cakes, of which we hear so much in Mexico..a tortillia is indispensable at least once a day for all classes.
1854 J. L. STEPHENS Centr. Amer. 29 The people live exclusively upon tortillas, flat cakes made of crushed Indian Corn, and baked on a clay griddle.
 
Thomas Gage’s
Travels in the New World
edited by J. Eric S. Thompson
Norman, OK: University of Oklahoma Press
1958
(The English-American His Travail by Sea and Land
Or, A New Survey of the West-India’s
London: R. Cotes
1648)
Pg. 222: 
But if their means will not reach to frijoles, their ordinary fare and diet is their tortillas (so they call thin round cakes made of maize dough). These they eat hot from an earthen pan, whereon they are soon baked with one turning over the fire, and they eat them alone either with chile and salt, and dipping them in water and salt with a little bruised chile.

A General Collection of the Best aand Most Interesting Voyages and Travels in All Part of the World
by John Pinkerton
London: Longman, Hurst, Rees, and Orme
1812
Volume the Thirteenth
Pg. 753:
Travels to Guaxaca*
by M. Nicolas Joseph Thiery de Menonville
*The same with Oaxaca, pronounced “Hooah”-haca.
(No date is given here, but the travels began in 1777—ed.)
 
Pg. 794:
These tordillas are cakes made of maize, first boiled in water, into which a handful of lime is cast to soften the exterior skin; the skin is afterwards washed off, and the peeled maize is crusted with a cylindrical stone, by rolling it over a flat one eighteen inches long by ten broad; after this first process, it is kneaded with the hand, and rounded and flattened to the thickness of about four lines; it is then baked on a stone or iron plate, heated for the purpose, and turned, that both sides may be properly baked; in two minutes the cake is made.  It is always an insipid food, but very stomachic, never causes indigestion, and at no time occasioned me any inconvenience.  In a family consisting of two women and five or six men, the former are constantly employed, morning and night, in preparing tordillas; five or six are requisite for one person at each meal, and they are constantly eaten new.
 
Pg. 802: 
...immediately another tordilya was served up, covered with an egg and chili: the latter dish I found excellent, and paid for with another real.I saw they were preparing me still others, but I made them signs to desist.
 
Tordilyas have before been noticed: they form the chief food of the Indians. As for chili it is a Mexican sauce made of pimento and tomatas, or love-apples, pounded together in a mortar, and mixed with salt and water: it is the common sauce, and (Pg. 803—ed.) indifferently for bread, meat and fish, and is the most delicate ragout known to these worthy people. Those who are in easy circumstances, always keep it by them to eat their tordilyas with, which are without it insipid. The Indian when he has no tomatas, knowing without doubt the affinity between them and nightshade and physalis, or the winter-cherry, substitutes alkekengi, or the winter-cherry, as I frequently remarked on my way, a circumstance which put me on my guard in eating this sauce.