norm

1. That which is normal or typical. · Unemployment is the norm in this part of the country.
2. A rule that is imposed by regulations and/or socially 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. if v ne 0 then ‖v‖ ne 0;
5. given a scalar k, ‖kv‖=|k|·‖v‖, where |k| is the absolute value of k;
6. given two vectors v,w, ‖v+w‖<‖v‖+‖w‖ (the triangle inequality).
7. Any of several generalizations of the above: a field norm, ideal norm, etc.
8. An element of the image of some (generalized) norm, the element then said to be from the norm in question, or from the structure which gave rise to the norm.

Plural norms