perioder

Perioder is a word used in Danish, Norwegian and Swedish to denote a span of time or a distinct phase. It is the plural form; the corresponding singular forms are periode in Danish and Norwegian and period in Swedish. The word is cognate with the English term period and derives from Latin periodus, via Greek periodos, originally meaning a circuit or cycle.

Uses: In everyday language, perioder describes stretches such as school holidays, work quarters, or phases in a project. In historical and scientific contexts, it designates larger divisions of time, such as geological periods (the Cambrian, Jurassic), historical periods (the Renaissance period), and astronomical periods (the orbital period of a planet).

Geology note: In geology, a period is a subdivision of an era, with eras containing multiple periods and periods further subdivided into epochs and ages. The standard hierarchy is eon > era > period > epoch > age.

Language and usage: The exact spelling and grammatical forms vary by language; note that perioder in Danish, Norwegian, and Swedish is not the same as the English plural periods. The term is commonly used across disciplines to refer to recognizable phases or intervals, whether in science, history, education, or everyday life.