standard; norm; criterion · (adjective) standard · good; correct; conforming to a standard

The criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.

We tried to come up to the standard.

Standard Chinese, commonly referred to as Mandarin, is based on Pekinese.

There are many people in the world studying English, so English people are used to learners' non-standard accents, their grammatical errors and so on.

You have to learn standard English.