What is the meaning of the word "standard"?

Definitions:

an upright pole or beam (especially one used as a support) noun
- distance was marked by standards every mile
commonly used or supplied adjective
- standard procedure
conforming to the established language usage of educated native speakers adjective
- standard English (American)
established or well-known or widely recognized as a model of authority or excellence adjective
- a standard reference work
regularly and widely used or sold adjective
- a standard size
the ideal in terms of which something can be judged noun
- they live by the standards of their community