Definition: any number of entities (members) considered as a unit
Similar words: abstract entity, abstraction
Definition: a general concept formed by extracting common features from specific examples
Synonyms: grouping
Definition: the activity of putting things together in groups
Similar words: activity
Definition: any specific behavior
Usage: they avoided all recreational activity
Synonyms: pigeonholing, grouping
Definition: a system for classifying things into groups
Similar words: classification system
Definition: a system for classifying things