When does a lettuce become salad?

Here's why:

* Salad is a dish made of various ingredients, often including leafy greens like lettuce.

* Lettuce is a type of leafy green vegetable.

Think of it like this:

* Flour is an ingredient in bread.

* Eggs are an ingredient in cake.

You wouldn't say that flour becomes bread or eggs become cake. Similarly, lettuce doesn't become salad. It's just one component of a salad.