norm

ot noun

1. That which is normal or typical. Unemployment is the norm in this part of the country.
2. A rule that is enforced by members of a community. Not eating your children is just one of those societal norms.
3. A sentence with non-descriptive meaning, such as a command, permission or prohibition.
4. A function, generally denoted v\mapsto\left|v\right| or v\mapsto\left\|v\right\|, that maps vectors to non-negative scalars and has the following properties:

fe’l verb

1. To endow (a vector space, etc) with a norm.