What does fortnight mean?
A fortnight is a unit of time equal to two weeks, or fourteen days and nights. The word is a fixture of everyday life in Britain, Ireland, Australia, New Zealand, and other countries shaped by British English, where it is used casually for anything from pay cycles ('paid fortnightly') to holidays ('a fortnight in Spain') to deadlines ('due in a fortnight'). In the United States it survives mainly as a quaint literary curiosity, since Americans overwhelmingly say 'two weeks' instead. Its charm lies in its origin: it descends from an ancient Germanic habit of measuring spans of time in nights rather than days — 'fortnight' is simply a compressed form of 'fourteen nights,' just as the older 'sennight' meant 'seven nights,' or one week. For readers outside North America, it remains a perfectly ordinary, neutral term; for Americans, using it adds a distinctly British flavour to speech and writing.
nounA period of two weeks, or fourteen days and nights.
- A period of fourteen days; two consecutive weeks.
"The festival runs for a fortnight every summer."
"We're heading to the coast for a fortnight in August."
"The committee meets once a fortnight to review applications."
Standard pluralization applies; used when referring to multiple two-week periods, as in durations or recurring intervals.
"The project was completed in three fortnights."
Before clocks and calendars ruled daily life, the English counted time in nights, not days — and 'fortnight' literally means 'fourteen nights.'
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fortnight
'Fortnight' derives from the Old English 'fēowertīene niht', meaning 'fourteen nights', reflecting an early Germanic convention of reckoning time by nights rather than days. It was worn down through Middle English into the single compound still used today. Its sibling word 'sennight', from 'seven nights' meaning one week, follows exactly the same pattern but has fallen out of use. Related Germanic number-and-time formations include 'fourteen' itself and the now-archaic 'twelvemonth', meaning a year.
Related word forms
How fortnight is actually used
'Fortnight' is standard everyday vocabulary in Britain, Ireland, Australia, New Zealand, and much of the former British Empire, but it is largely unfamiliar to American speakers, who say 'two weeks' instead. It carries a slightly traditional, homey tone and appears often in scheduling, rental, payroll, and holiday contexts.
Easily confused with fortnight
Sennight means a week (seven nights), whereas fortnight means two weeks (fourteen nights) — both are archaic-style terms built on counting by nights.