classifier

noun

1. Someone who classifies.

   “He was a model of anal defensiveness: fastidious in his dress and appearance, a collector and putter of things in order, a classifier and labeler.”

2. A word or morpheme used in some languages (such as CJKV languages and sign languages), in certain contexts (such as counting), to indicate the semantic class to which something belongs.
3. A machine that separates particles or objects of different size or density.
4. A program or algorithm that classifies.
5. A metaclass used to group other entities having common features.

   “A classifier can have several types of extra information attached to it via a UML mechanism called adornments.”

   “The owner scope of a feature specifies whether the feature appears in each instance of the classifier or whether there is just a single instance of the feature for all instances of the classifier.”

   “The figure also shows that instances can be associated with a classifier Behavior, which represents the behavior that active objects start executing when created.”