Words about time: punctual, ephemeral, diurnal and more

Words about time describe punctuality (punctual, prompt, tardy), duration (ephemeral, perennial, eternal), frequency (diurnal, sporadic, intermittent), order (chronological, simultaneous, subsequent) and past and future (anachronism, obsolete, imminent). Many come from the Greek chronos and Latin tempus, both meaning time.

Greek root	chronos, 'time'
Latin root	tempus, 'time'
'Punctual' comes from	Latin punctum, 'point'
'Clock' comes from	Medieval Latin clocca, 'bell'
a.m. and p.m.	ante meridiem and post meridiem, 'before and after midday'
Biannual vs biennial	Twice a year vs every two years

English borrowed most of its time vocabulary from two words: the Greek chronos and the Latin tempus. Here are the most useful time words, grouped by meaning, with a short definition and where each comes from.

Other ways to say punctual

Word or phrase	Meaning	Register
on time	At the agreed time.	Everyday
on the dot	Exactly at the stated time: 'at 4:00 on the dot.'	Informal
sharp	Precisely at that time: 'The meeting starts at 9 sharp.'	Informal
on the nose / on the button	Exactly on time.	Informal, mainly US
in good time	Early enough, with no rush.	Everyday
with time to spare	Earlier than needed.	Everyday
on schedule	As planned, not late.	Everyday
prompt	Quick to act or arrive at the right time.	Neutral
timely	At a useful or appropriate time.	Neutral
timeous	In good time.	Formal, mainly Scottish
just in time / under the wire	At the last possible moment, but not late.	Informal
punctuality, promptness, timeliness	The nouns: the habit or quality of being on time.	Neutral

The opposites are late, tardy, belated, overdue and behind schedule. More on the word itself: what punctual means and where it comes from.

Being on time

Word	Meaning	Origin
punctual	Arriving or happening at the agreed time.	Latin punctum, 'point'
prompt	Done without delay.	Latin promptus, 'brought forth, ready'
timely	Happening at a suitable or useful time.	Old English tima, 'time'
tardy	Late; slower than expected.	Latin tardus, 'slow'
belated	Coming later than it should have.	be- + late
overdue	Not yet done or arrived after the expected time.
premature	Happening too soon.	Latin praematurus, 'ripe too early'
dilatory	Slow to act; tending to delay.	Latin dilatorius, 'delaying'
expeditious	Quick and efficient.	Latin expedire, 'to set free'
posthaste	As quickly as possible.	From 'haste, post, haste,' written on urgent letters

How long something lasts

Word	Meaning	Origin
ephemeral	Lasting a very short time.	Greek ephēmeros, 'lasting a day'
fleeting	Passing quickly.
transient	Staying only briefly.	Latin transire, 'to go across'
transitory	Not permanent.	Latin transitorius
evanescent	Quickly fading away.	Latin evanescere, 'to vanish'
momentary	Lasting a moment.	Latin momentum, 'movement, instant'
temporary	Lasting for a limited time.	Latin tempus, 'time'
perennial	Lasting a long time, or returning every year.	Latin per + annus, 'through the year'
perpetual	Never ending or changing.	Latin perpetuus, 'continuous'
eternal	Without beginning or end.	Latin aeternus, from aevum, 'age'
interminable	Seeming to go on forever.	Latin in- + terminare, 'without end'
protracted	Lasting longer than expected.	Latin protrahere, 'to draw out'
chronic	Persisting for a long time.	Greek chronos, 'time'

How often something happens

Word	Meaning	Origin
diurnal	Daily; or active in the daytime.	Latin diurnus, from dies, 'day'
nocturnal	Active at night.	Latin nocturnus, from nox, 'night'
quotidian	Daily; ordinary.	Latin cotidie, 'every day'
periodic	Happening at regular intervals.	Greek periodos, 'cycle'
cyclical	Happening in repeated cycles.	Greek kyklos, 'circle'
intermittent	Stopping and starting at irregular intervals.	Latin intermittere, 'to leave off'
sporadic	Happening now and then, irregularly.	Greek sporadikos, 'scattered'
incessant	Continuing without a pause.	Latin in- + cessare, 'not ceasing'
biannual	Twice a year.
biennial	Every two years.	Latin bi- + annus
centennial	Relating to 100 years; a 100th anniversary.	Latin centum, 'hundred'
millennial	Relating to 1,000 years.	Latin mille, 'thousand'

Order and timing

Word	Meaning	Origin
chronological	Arranged in the order things happened.	Greek chronos + logos
sequential	Following one after another.	Latin sequi, 'to follow'
simultaneous	Happening at the same time.	Latin simul, 'at the same time'
synchronous	Happening at the same rate or time.	Greek syn- + chronos, 'same time'
concurrent	Running alongside at the same time.	Latin concurrere, 'to run together'
contemporaneous	Existing in the same period.	Latin con- + tempus
contemporary	Of the same time; or of the present day.	Latin con- + tempus
antecedent	Something that comes before.	Latin antecedere, 'to go before'
precursor	A forerunner.	Latin praecurrere, 'to run ahead'
subsequent	Coming after.	Latin subsequi, 'to follow closely'
interim	The time in between; temporary.	Latin interim, 'meanwhile'
hiatus	A pause or gap.	Latin hiare, 'to gape'

Past and future

Word	Meaning	Origin
anachronism	Something placed in the wrong time period.	Greek ana- + chronos, 'against time'
archaic	Very old or no longer used.	Greek archaios, 'ancient'
obsolete	No longer in use.	Latin obsoletus, 'worn out'
antiquated	Old-fashioned.	Latin antiquus, 'ancient'
immemorial	Older than anyone can remember.	Latin in- + memoria
bygone	Belonging to the past.
erstwhile	Former.	Old English ǣr, 'before'
nascent	Just beginning to exist.	Latin nasci, 'to be born'
imminent	About to happen.	Latin imminere, 'to overhang'
impending	About to happen, often something bad.	Latin impendere, 'to hang over'
posthumous	Happening after someone's death.	Latin postumus, 'last'
retroactive	Taking effect from a date in the past.	Latin retro, 'backward'
prescient	Knowing about events before they happen.	Latin praescire, 'to know beforehand'

Words for measuring time

Word	Meaning	Origin
chronometer	A highly accurate clock, especially one used at sea.	Greek chronos + metron, 'measure'
horology	The study and making of clocks.	Greek hōra, 'hour'
sidereal	Measured by the stars (a sidereal day is about 23 h 56 min).	Latin sidus, 'star'
equinox	When day and night are about equal.	Latin aequus + nox, 'equal night'
solstice	When the sun reaches its highest or lowest point.	Latin sol + sistere, 'sun stands still'
meridian	A line of longitude; also midday.	Latin meridies, 'midday'
epoch	A period marked by notable events; a reference date.	Greek epochē, 'pause, fixed point'
era	A long, distinct period of history.	Late Latin aera, 'counters, number'
eon	An immensely long time.	Greek aiōn, 'age'
temporal	Relating to time.	Latin tempus
tempo	Speed or pace.	Italian, from Latin tempus

The roots behind time words

Root	Language	Meaning	English words
chronos	Greek	time	chronic, chronicle, chronology, synchronize, anachronism, chronometer
tempus	Latin	time	temporal, temporary, contemporary, extemporaneous, tempo
hōra	Greek, via Latin	hour, season	hour, horology, horoscope
dies	Latin	day	diurnal, journal (via diurnalis), sojourn, meridian
annus	Latin	year	annual, anniversary, perennial, biennial, millennium
aevum	Latin	age	eternal, coeval, medieval (medium aevum, 'middle age')
meridies	Latin	midday	a.m. (ante meridiem, 'before midday') and p.m. (post meridiem)

Time idioms and where they come from

At the eleventh hour: At the last possible moment. From the parable of the workers in the vineyard (Matthew 20), where the last workers are hired at the eleventh hour.
In the nick of time: Just in time. Probably from 'nick' meaning a notch, as on a tally stick, so the exact point.
Time flies: Time passes quickly. From the Latin 'tempus fugit,' after a line by the poet Virgil.
Around the clock: All day and all night.
Against the clock: Racing to finish before a deadline.
Behind the times: Old-fashioned; not up to date.
Buy time: Delay something to gain an advantage.
Call it a day: Stop working for now.
Kill time: Do something just to make time pass.
Once in a blue moon: Very rarely. A 'blue moon' today usually means a second full moon in one calendar month, which happens about every 2½ years.
The crack of dawn: Very early in the morning.
The witching hour: Midnight, or the dead of night.

The word clock itself comes from Medieval Latin clocca, “bell,” because the first mechanical clocks struck bells rather than showing a face. See who invented the mechanical clock.

Questions people ask

What is a word for always being on time?

Punctual. Someone who is reliably on time is punctual; the quality is punctuality.

What are synonyms for punctual?

Prompt, timely and on time. Informally: on the dot, sharp, on the nose, on schedule, in good time.

What's the difference between biannual and biennial?

Biannual means twice a year. Biennial means once every two years.

What does ephemeral mean?

Lasting a very short time. It comes from the Greek for 'lasting only a day.'

Sources

Last updated October 18, 2026. Found an error? Tell us.