Nychthemeron , occasionally nycthemeron or ''nuchthemeron'', is a period of 24 consecutive

hour An hour (symbol: h; also abbreviated hr) is a unit of time conventionally reckoned as of a day and scientifically reckoned between 3,599 and 3,601 seconds, depending on the speed of Earth's rotation. There are 60 minutes in an hour, and 24 ...

s. It is sometimes used, especially in technical literature, to avoid the ambiguity inherent in the term ''

day A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours, 1440 minutes, or 86,400 seconds. In everyday life, the word "day" often refers to a solar day, which is the length between two ...

''. It is the period of time that a

calendar A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single and specific day within such a system. A calendar is also a phy ...

normally labels with a date, although a nychthemeron simply designates a time-span that can start at any time, not just midnight.

Etymology

It is a

loanword A loanword (also loan word or loan-word) is a word at least partly assimilated from one language (the donor language) into another language. This is in contrast to cognates, which are words in two or more languages that are similar because ...

from

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...

(), which appears in the New Testament. This is a noun use of the neuter singular form of , from (, “night”) + (, “day”).

In other languages

Some languages have a word for 24 hours, or more loosely a day plus a night in no particular order. Unlike a calendar date, only the length is defined, with no particular start or end. Furthermore, these words are considered basic and native to these languages, so unlike ''nychthemeron'' they are not associated with

jargon Jargon is the specialized terminology associated with a particular field or area of activity. Jargon is normally employed in a particular communicative context and may not be well understood outside that context. The context is usually a partic ...

. Words for 24 hours are listed in the middle column. For comparison, the word for ''day'', in the meaning of

daytime Daytime as observed on Earth is the period of the day during which a given location experiences natural illumination from direct sunlight. Daytime occurs when the Sun appears above the local horizon, that is, anywhere on the globe's hemi ...

, the ''sunlit state'', the opposite of night, is also listed in the rightmost column: The word , as in the Nordic languages, is etymologically the same as ''day'' in English.

References

Units of time Calendars {{time-stub