Taxonomy n. : That division of the natural sciences which treats of the classification of animals and plants; the laws or principles of classification.

Example:
What is the difference between typology and Taxonomy?

Taxonomy
taxonomy, folk taxonomies, car, ranks, taxa, relationships, science, vehicle, subtype, free encyclopedia, taxonomic scheme, supertype, constraints, hierarchies, taxonomic ranks, traits, similarity, military.

Defination from the web:
... Taxonomy uses taxonomic units, known as taxa (singular taxon) ...