APA Dictionary of Psychology

domain

Updated on 04/19/2018

the class of entities or events that constitutes the subject matter of a science or other discipline.
a field of mastery, dominance, or endeavor.
in biological taxonomy, the highest category used in some classification systems, comprising one or more kingdoms. Three domains are recognized: Archaea (archaebacteria), Bacteria, and Eukarya (including animals, plants, fungi, and protists).
in set theory, the set of elements over which a function is defined.

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