Cacao, pronounced by the Olmecs as kakawa, dates to 1000 BC or earlier. The word "chocolate" entered the English language from Spanish in about 1600. The word entered Spanish from the word chocol?tl in Nahuatl, the language of the Aztecs. The origin of the Nahuatl word is uncertain, as it does not appear in any early Nahuatl source, where the word for chocolate drink is cacahuatl, "cacao water". It is possible that the Spaniards coined the word (perhaps in order to avoid caca, a vulgar Spanish word for "faeces") by combining the Yucatec Mayan word chocol, "hot", with the Nahuatl word atl, "water". Another proposed etymology derives it from the word chicolatl, meaning "beaten drink", which may derive from the word for the frothing stick, chicoli. The term "chocolatier", for a chocolate confection maker, is attested from 1888.

Mesoamerican usage

Chocolate has been prepared as a drink for nearly all of its history. For example, one vessel found at an Olmec archaeological site on the Gulf Coast of Veracruz, Mexico, dates chocolate's preparation by pre-Olmec peoples as early as 1750 BC. On the Pacific coast of Chiapas, Mexico, a Mokaya archaeological site provides evidence of cacao beverages dating even earlier, to 1900 BC. The residues and the kind of vessel in which they were found indicate the initial use of cacao was not simply as a beverage, but the white pulp around the cacao beans was likely used as a source of fermentable sugars for an alcoholic drink.

An early Classic-period (460–480 AD) Mayan tomb from the site in Rio Azul had vessels with the Maya glyph for cacao on them with residue of a chocolate drink, suggests the Maya were drinking chocolate around 400 AD. Documents in Maya hieroglyphs stated chocolate was used for ceremonial purposes, in addition to everyday life. The Maya grew cacao trees in their backyards, and used the cacao seeds the trees produced to make a frothy, bitter drink.

By the 15th century, the Aztecs gained control of a large part of Mesoamerica and adopted cacao into their culture. They associated chocolate with Quetzalcoatl, who, according to one legend, was cast away by the other gods for sharing chocolate with humans, and identified its extrication from the pod with the removal of the human heart in sacrifice. In contrast to the Maya, who liked their chocolate warm, the Aztecs drank it cold, seasoning it with a broad variety of additives, including the petals of the Cymbopetalum penduliflorum tree, chile pepper, allspice, vanilla, and honey.

The Aztecs were not able to grow cacao themselves, as their home in the Mexican highlands was unsuitable for it, so chocolate was a luxury imported into the empire. Those who lived in areas ruled by the Aztecs were required to offer cacao seeds in payment of the tax they deemed "tribute". Cocoa beans were often used as currency. For example, the Aztecs used a system in which one turkey cost 100 cacao beans and one fresh avocado was worth three beans.

The Maya and Aztecs associated cacao with human sacrifice, and chocolate drinks specifically with sacrificial human blood. One of the first Spanish accounts of chocolate is by the royal chronicler Gonzalo Fernández de Oviedo, describing chocolate drink he had seen in Nicaragua in 1528, mixed with achiote (Bixa orellana): "because those people are fond of drinking human blood, to make this beverage seem like blood, they add a little achiote, so that it then turns red. ... and part of that foam is left on the lips and around the mouth, and when it is red for having achiote, it seems a horrific thing, because it seems like blood itself."

European adaptation

Until the 16th century, no European had ever heard of the popular drink from the Central American peoples. Christopher Columbus and his son Ferdinand encountered the cacao bean on Columbus's fourth mission to the Americas on 15 August 1502, when he and his crew seized a large native canoe that proved to contain cacao beans among other goods for trade. Spanish conquistador Hernán Cortés may have been the first European to encounter it, as the frothy drink was part of the after-dinner routine of Montezuma. Jose de Acosta, a Spanish Jesuit missionary who lived in Peru and then Mexico in the later 16th century, wrote of its growing influence on the Spaniards:

Loathsome to such as are not acquainted with it, having a scum or froth that is very unpleasant taste. Yet it is a drink very much esteemed among the Indians, where with they feast noble men who pass through their country. The Spaniards, both men and women that are accustomed to the country are very greedy of this Chocolate. They say they make diverse sorts of it, some hot, some cold, and some temperate, and put therein much of that "chili"; yea, they make paste thereof, the which they say is good for the stomach and against the catarrh.

While Columbus had taken cacao beans with him back to Spain, chocolate made no impact until Spanish friars introduced it to the Spanish court. After the Spanish conquest of the Aztecs, chocolate was imported to Europe. There, it quickly became a court favorite. It was still served as a beverage, but the Spanish added sugar, as well as honey, to counteract the natural bitterness. Vanilla was also a popular additive, with pepper and other spices sometimes used to give the illusion of a more potent vanilla flavor. Unfortunately, these spices had the tendency to unsettle the European constitution; the Encyclopédie states, "The pleasant scent and sublime taste it imparts to chocolate have made it highly recommended; but a long experience having shown that it could potentially upset one's stomach," which is why chocolate without vanilla was sometimes referred to as "healthy chocolate." By 1602, chocolate had made its way from Spain to Austria. By 1662, Pope Alexander VII had declared that religious fasts were not broken by consuming chocolate drinks. Within about a hundred years, chocolate established a foothold throughout Europe.