hierarchy - a series of ordered groupings of people or things within a system; "put honesty first in her hierarchy of values"

biological science, biology - the science that studies living organisms

systematics - the science of systematic classification

cladisitic analysis, cladistics - a system of biological taxonomy based on the quantitative analysis of comparative data and used to reconstruct cladograms summarizing the (assumed) phylogenetic relations and evolutionary history of groups of organisms

classification, compartmentalisation, compartmentalization, assortment, categorisation, categorization - the act of distributing things into classes or categories of the same type