oppien

Oppien is the genitive plural form of the Finnish noun oppi, which means doctrine, teaching, or principle. The word is used to refer to a set of beliefs or to indicate a relation to those beliefs, rather than to individual lessons. In practice, oppien appears in contexts such as philosophy, religion, and scholarly writing when discussing doctrinal systems or schools of thought. The form reflects Finnish grammar, where the genitive plural suffix -ien is added to stems ending with -i, yielding oppien.

In usage, oppien is often found in phrases meaning “according to the teachings” (oppien mukaan) or when contrasting different sets of beliefs (oppien erimielisyydet). It can also be employed to name or describe doctrinal frameworks, such as interpretations or applications of a given teaching tradition. While oppi and oppiaineet (school subjects) are common terms in everyday language, oppien tends to appear in more formal or academic discussions about doctrine rather than in casual speech.

Related terms include oppi (singular), opillinen (doctrinal), oppineisuus (learnedness), and oppikirja (textbook). In educational contexts, oppiaineet are the school subjects, whereas oppien foregrounds the theoretical or doctrinal dimension of a belief system. For further reading, see oppi and oppineisuus to explore how Finnish uses related forms to express doctrine and knowledge.