意识形态（英语：Ideology，希腊语：ἰδεολογία），意为「理念（德语：Idee）或想像（德语：Vorstellung）的学说」希腊语：ἰδεο（形象）与希腊语：λογία（学说）。中文也译意识型态；周德伟译作意理 ；林毓生主张音译意译合一，译为意缔牢结，以避免对意识形态望文生义的附会）有两种具有本质性区别的涵义：

Ideology is a collection of doctrines or beliefs shared by members of a group. It can be described as a set of conscious and unconscious ideas which make up one's beliefs, goals, expectations, and motivations. An ideology is a comprehensive normative vision that are followed by people, governments, or other groups that is considered the correct way by the majority of the population, as argued in several philosophical tendencies (see political ideologies). It can also be a set of ideas proposed by the dominant class of society such as the elite to all members of society as suggested in some Marxist and critical-theory accounts. While the concept of "ideology" describes a set of ideas broad in its normative reach, an ideology is less encompassing than the ideas expressed in concepts such as worldview, imaginary and ontology.