What Is The Definition Of Pesto?

Dictionary definition

Short answer
There is a broad consensus among the world's most trusted dictionaries that pesto can be defined as an Italian sauce made from basil, pine nuts, cheese, garlic, and olive oil that is usually served with pasta.

Long answer
While precise wording differs, look for a pesto definition in the world’s most popular dictionaries, and you'll find a broad agreement. Here's what three of them say:

Oxford English Dictionary
A sauce of crushed herbs (usually fresh basil leaves), nuts (usually pine nuts), cheese, garlic, and olive oil, typically served with pasta.

Collins Dictionary
An Italian sauce made from basil, garlic, pine nuts, cheese, and olive oil.

Merriam Webster
A sauce made especially of fresh basil, garlic, oil, pine nuts, and grated cheese.

There is an alternative way to define pesto, though. The word (pronounced peh·stow) comes from the past participle of the Genoese verb pestâ (Italian: pestare), meaning “to pound” or "to crush." This is a reference to the pestle and mortar that cooks used to make the sauce long before food processors were invented.

We rather like the fact that the word "pesto" is based on a verb rather than a noun. To us, that means we can define pesto not just by its ingredients but also by the process required to make it. While it infuriates some traditionalists, we think this gives chefs as much poetic licence as they like to call their sauce a "pesto," even if their recipe contains different ingredients from traditional basil pesto.