Pesto means pounded in Italian, from the verb pestare, to crush or grind. The name describes the preparation method rather than the ingredients — traditional pesto alla genovese is made by grinding basil leaves, garlic, pine nuts, coarse salt, and hard cheese together in a marble mortar using a wooden pestle, then working in olive oil until the mixture reaches a smooth, dense consistency.
The Latin ancestor is pistare, a frequentative form of pinsere meaning to crush. This same root produced the English words pestle and piston, and the French pilon. All share the core idea of pounding or pressing — mechanical force applied repeatedly to break something down.
Pesto originated in Liguria, the crescent-shaped coastal region of northwest Italy centered on Genoa. Ligurian basil, grown in the mild microclimate between the Apennine mountains and the Mediterranean Sea, has a distinctively sweet, less peppery flavor than basil grown elsewhere. Genoese cooks claim this variety is essential to authentic pesto, and the sauce has been a regional staple since at least the mid-19th century.
Genoese sailors and merchants carried pesto on trading voyages because the oil and salt preserved the crushed basil for weeks. This portability helped spread the sauce along Mediterranean shipping routes long before it became internationally known.
Pesto entered English-language cookbooks in the mid-20th century but did not become widely popular in the United States and Britain until the 1980s and 1990s, during a broader wave of interest in Italian regional cooking. Today the word is applied loosely to any blended herb sauce — sun-dried tomato pesto, walnut pesto, kale pesto — which irritates Genoese traditionalists who maintain that pesto without Ligurian basil and pine nuts is simply not pesto at all.