Class

A class is a set, collection, group, or configuration containing members regarded as having certain attributes or traits in common; a kind or category.

A "social class" are individuals who are grouped together based on economic or political proportions. That would be referred to as a caste system.

The word "class" is frequently used in education to denote a group of students who are taught together because they have roughly the same level of academic development.

For the meaning of "class" relating to the US Senate, see class.