* A straight rod or reed: This is the most literal meaning, and forms the basis of its other uses.
* A rule or standard: This is the most common meaning in many contexts. It refers to a standard of measurement, a principle, a norm, or a law. This meaning is crucial for understanding its use in terms of canonical scripture, artistic rules, or even musical scales.
* A list or catalogue: A related meaning, deriving from the idea of a standardized or ordered list.
* A measuring instrument: An extension of the "rule or standard" meaning.
The specific meaning of κανών (kanon) depends heavily on the context in which it's used.