function: (mathematics) a mathematical relation such that each element of a given set (the domain of the function) is associated with an element of another set (the range of the function)
abstraction: a general concept formed by extracting common features from specific examples
protoctista: in most modern classifications, replacement for the Protista; includes: Protozoa; Euglenophyta; Chlorophyta; Cryptophyta; Heterokontophyta; Rhodophyta; unicellular protists and their descendant multicellular organisms: regarded as distinct from plants and animals