basis
In Italian, the word 'base' is used to express the same concept as 'basis' in English. It can refer to a fundamental principle, theory, or foundation upon which something is built or developed. For example, 'La teoria della relatività è la base per comprendere la fisica moderna.' (The theory of relativity is the basis for understanding modern physics.)
The base for a good pizza is the dough.
In this sentence, 'base' is used in a culinary context. A good pizza dough is essential, or the 'base', for a good pizza.
It is important to have a solid base of knowledge.
This sentence means that having a 'base', or foundational level, of knowledge is important. This could be in relation to any subject or skill.
Baseball is a very popular sport in America.
In this sentence, 'base' is part of the word 'baseball', which is a popular sport in the United States. This usage of 'base' does not conform to the usual expectation of the word 'base' as meaning 'foundation' or 'starting point'.