Since tacos are made of corn tortillas, and corn comes from the Americas, I expected the unusual-sounding word taco to have Native American origins. And, indeed, the Aztecs are thought to have eaten tacos. But that's not where the word comes from. When the Spanish encountered the delicacy in the sixteenth century, they called it taco, their word for "a light lunch". This is a bit of a metaphor; the literal meaning is "plug", and by eating a taco you could put a proverbial plug in your hunger, as it were (this strikes me as ironic because tacos these days need plugs to stop all the food from falling out). This comes from the Old French word tache, meaning "nail", which in turn came from Middle Low German zacke, meaning "sharp point". Apparently that got less dull over time. This is from Proto-Germanic tag, from Proto-Indo-European dek, both with connotations of sharp objects. Probably due to increased commercialization of the food in the era of globalization, usage of the word taco has been increasing almost exponentially in English since about the 1960s.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.