ANTHROPOCENE: The current geological epoch, defined by the dominant influence of human activity on the Earth’s environment and climate.
ASTRONOMICAL TWILIGHT: When the Sun is 18 degrees below the horizon. This is the period of first light in the morning and when the sky is almost dark in the evening. See Civil and Nautical Twilight.
BLUE HOUR, THE: The unspecific period of Twilight when natural light appears to have a strong blue hue.
BORROWED LIGHT (archaic): Artificial light.
CHANGE: The process of transformation, of becoming something other.
CHRONOBIOLOGY: The science of body clocks or biological circadian rhythms.
CHRONOTYPE: A particular individual’s type of body clock or circadian cycle.
CIRCADIAN: Happening in a cycle that follows the time the Earth takes to circle the Sun (i.e. occurring in an approximately 24 standard-hour cycle).
CIVIL TWILIGHT: When the Sun is 6 degrees below the horizon. Civil Twilight is the lightest portion of Twilight. It precedes Dawn and follows Sunset. See Astronomical and Nautical Twilight.
COCK-CROW (archaic): The period shortly before Dawn.
COCKNEY (Cockney): Time. Derived from “Time” rhymed with “Cockney Rhyme”. For example, “Have you got the Cockney?”
CONTEXT-SPECIFIC TIME: The term given to time judged by local processes and events, rather than by an external or abstract measure such as the standard clock.
CREPUSCULAR: Of Twilight; the adjective to describe animals and other entities associated with Twilight.
DARKLING (archaic): Darkening; potentially dangerous.
DAWN: The first light that ushers in Astronomical Twilight.
DEADLINE: Time limit. Originally the prison camp term for its outer limit. Guards were instructed to shoot any prisoner who crossed the deadline.
DEAD OF NIGHT, THE: Anciently, the period of night after midnight and before first light, considered to be the darkest point in the circadian cycle. See Intempesta.
DIURNAL: Active during the day and sleeping at night. Used to define typical human behaviour. Antonym: nocturnal.
DUSK: The darkest point of Twilight, on the cusp of Night.
ECOZOIC ERA: Thomas Berry's term for a future in which “human conduct will be guided by the ideal of an integral earth community [that includes] all the human and non-human components that constitute the planet Earth”.
EQUINOX: The twice-yearly date on which day and night are of equal length.
EREMOZOIC ERA: EO Wilson's term for the Age of Loneliness, a future biological epoch where human activity extinguishes nearly all life on Earth (The Creation, 2006).
ENTROPY: Without order, predictability; gradual decay; slow disintegration into disorder.
ESCHATOLOGY (Christian traditions): Belief(s) regarding the events that will end the world or human history.
ETERNAL: Without change; without end.
FIRST SLEEP: According to historian A. Roger Ekirch, the first of two sleeps that pre-industrial people would take each night. His research suggests that the roughly hour-long interval of wakefulness between first sleep and “morning sleep” was a time for watchfulness, prayer, reflection, dream interpretation and sex.
GIBBOUS: The adjective describing a moon that is more than half full.
GLOAMING: Twilight or Dusk.
GÖKOTTA (Swedish, pronounced yo’-kOt-tah): The act of rising early to hear the first birdsong; a dawn picnic.
GOLDEN HOUR, THE: The unspecific period of time following Sunrise or preceding Sunset when light takes on a reddish hue.
GRACE NOTE: An ornamental musical note added without fixed beat or duration to a composition.
GREENWICH MEAN TIME (GMT): The average local solar time at Greenwich in London. GMT gives accurate local solar time for Greenwich on just four days of the year.
HANAMI (Japanese): The ritual of taking time to enjoy the ephemeral beauty of flowers, most often cherry blossom. Hanami may take the form of a pilgrimage following the wave of flowering trees as the Spring thaw travels north.
HARVEST MOON: When the full moon casts light for longer periods around the Autumn Equinox in September.
HEARTBEAT: One pulsation of the heart; perhaps the first and principle measure of time for all animals; a fleeting moment; a unifying or animating force. Statistically speaking, all animals live for roughly a billion heartbeats (SJ Gould). Exceptions include humans who live for approximately three billion.
HISTORY: Time as it is lived.
HOROLOGE: A timepiece, such as a clock.
INTEMPESTA (Latin): The name given by the ancient Romans to the period of the night between midnight and first light. Literally, time without time. See Dead of Night and Witching Hour.
JIFFY: A short while. Possibly from slang for lightening.
KAIROS (Greek): The timely or opportune moment; the right time; the weather.
KODAWARI (Japanese): The mindful and rigorous honing of a craft over time towards perfection.
MIDDAY: The exact moment when the Sun is highest in the sky above a given place. This defines local solar noon. (Greenwich local solar noon matches GMT noon on only four days of the year. Hence the Mean in GMT.)
MIDNIGHT: Exactly half way between Sunrise and Sunset.
MIDSUMMER’s Day: See Summer Solstice.
MONOCHRONIC (Island dialect): An adjective to describe: time reduced to a commodity (as in “Time is Money”); time lived focusing on future outcomes with less value given to the present; the measurements of the mechanical clock, particularly those dissociated from solar, lunar or biological rhythms; regimes of time that enforce any or all of the above. See its antonym Stereochronic.
MURMURATION: The name given to the twilight dance made by thousands of starlings coming together to roost at predictable times of the day. Also known as a starling spectacular.
NAUTICAL TWILIGHT: When the Sun is 12 degrees below the horizon, and the rough shape of objects can still be made out. This follows Civil Twilight in the evening, and Astronomical Twilight in the morning.
NIGHT FOGS (archaic): The miasma that was thought to drop from the sky with nightfall.
NOCTAMBULIST: Sleep walker.
NOON: See Midday.
PEAR DROP: The season when pear trees naturally release their least promising fruit.
PENUMBRA: In partial shadow. During a solar eclipse, a person in penumbra sees a partial eclipse. From the Latin paene (almost) and umbra (shadow).
PIG (archaic): A verb to describe sharing a bed with others who may or may not be members of one’s immediate family, as was common practice. For example, “Five of us pigged in one wide bed”.
PROCRASTINATION: Doing less urgent, easier or more pleasing tasks rather than those which require greater immediacy, effort or difficulty.
RETROMANCY: Divination (attempting to read the future from supernatural signs) by looking over your shoulder. Perhaps related to the ancient idea that the future lay behind and the past in front of you.
RHAPSODY: A free-flowing composition or narrative that combines highly contrasting and unpredictable elements and registers, in contrast to a unified form progressing through predictable stages.
SEASON: A division of time. Today, most commonly used to describe natural climatic periods resulting from the Earth’s changing orbit of the Sun. Formerly used more broadly to refer to a particular time characterised by a distinct set of qualities. For example, night-time was also known as the night-season.
SOLAR TIME: Time measured by when the Sun is highest in the sky above a particular place at noon. As opposed to standard time, which is an ideal measure based on averages. See Greenwich Mean Time.
SUMMER SOLSTICE: One of two days of the year on which the Sun seems to change direction. On this day the Sun appears at its highest point in the sky for the year. After this date the days grow shorter. From the Latin Sol (Sun) and Sistere (to stand still). Also known as Midsummer’s Day. See Winter Solstice.
SPRING TIDE: The time when the ocean tide differs most between its highest and lowest due to the relationship between Earth, Moon and Sun. The term does not refer to the solar season, but to the tide seeming to “spring out”.
STEREOCHRONIC (Island dialect): An adjective to describe: multiple and varied states of time; time fully lived; time not defined by the mechanical clock but by local events and processes. See its antonym Monochronic.
SUNRISE: When the Sun rises above the horizon, marking the end of Civil Twilight.
TAX YEAR: In the UK, the financial year that starts on 6 April. This apparently arbitrary administrative date derives from the old New Year, which fell on Spring Equinox. It became detached from the true solar date of Spring Equinox in transition to the Gregorian Calendar.
TEMPONAUT: Time traveller.
TEMPS, LE (French): Time; the weather.
TIDE (archaic): A duration; a season; a repeated action or event; a fitting time; a defined period (eg, eventide or Yuletide).
TIDEFUL (archaic): Opportune, convenient, timely.
TIDY (archaic): In tide; in season; in time; timely.
TIMELY: Happening at the proper time.
TWILIGHT: The interval between Sunset and Nightfall, when the Sun sinks below the horizon but still lights the sky.
TWILIGHT REST (archaic): The period of the Scandanavian day when it is too dark to work but considered too early to light a lamp.
WANING: To describe the Moon when it seems to be growing smaller.
WAXING: To describe the Moon when it seems to be growing bigger.
WIDDERSHINS (Early Modern English): The act of moving anti-clockwise against the apparent course of the Sun; running counter to good sense. (It was once considered bad luck to move widdershins round a church.)
WINTER SOLSTICE: The day of the year when, in Britain and other latitudes, the Sun appears to change direction in the sky and the days start to become longer. See Summer Solstice.
WITCHING HOUR, THE: Midnight, when anciently witches and spirits were thought most likely to appear.
ZEMAN (Hebrew): Time, as in the abstract standard entity against which we measure events; formerly, appointment, as in time defined by lived events. See Context-Specific Time.
ZEITGEBER (German): An environmental time trigger. For example, the dipping of the Sun below the horizon, which signals time to sleep for the body clock of a diurnal animal. Literally, time-giver.
ZEITGEIST (German): The spirit of the times.
ZUGENRUHE (German): The restlessness that tugs at birds to migrate back to their nesting grounds for Spring.