What does fortnightly mean?
Fortnightly describes anything that happens, appears, or is done once every two weeks — an interval known as a fortnight. It functions as an adjective ('a fortnightly meeting'), an adverb ('we are paid fortnightly'), and, less commonly, a noun denoting a magazine or newspaper published every two weeks. The word is firmly rooted in British, Australian, and wider Commonwealth usage and is much less common in American English, where the ambiguous term 'biweekly' tends to be used instead. Because 'biweekly' can mean either twice a week or every two weeks, 'fortnightly' has real value as a precise alternative: it can mean only one thing. Its pedigree is distinctly old — it derives from 'fortnight', itself from the Old English for 'fourteen nights', reflecting an ancient way of counting time by nights rather than days. In everyday speech it is neutral and practical, appearing most often in discussions of pay schedules, publication cycles, and recurring appointments.
Occurring, appearing, or done once every two weeks.
"The journal publishes fortnightly issues throughout the year."
At intervals of two weeks; once every fortnight.
"The gardener comes fortnightly to tend the grounds."
A periodical published once every two weeks.
"He subscribed to a literary fortnightly based in London."
This noun sense is now relatively uncommon, largely associated with historical or specialist periodicals.
'Fortnightly' is one of the rare English words that counts time by nights rather than days — a survival of how the Anglo-Saxons measured weeks, fourteen nights at a time.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fortnightly
Fortnightly is formed from 'fortnight' plus the suffix '-ly'. 'Fortnight' comes from the Old English 'fēowertīene niht', meaning 'fourteen nights', reflecting the Germanic custom of reckoning time by nights rather than days; the parallel formation 'sennight' (seven nights, i.e., a week) survives from the same tradition. The compound 'fortnightly' emerged in English usage to describe two-week intervals, with its use for biweekly publications becoming established in the eighteenth and nineteenth centuries.
How fortnightly is actually used
The word is far more common in British, Australian, and other Commonwealth English than in American English, where 'biweekly' or 'every two weeks' is preferred despite its ambiguity. It carries a neutral, often practical register, especially familiar in payroll and scheduling contexts in the UK and Australia. Note that 'bimonthly' suffers the same ambiguity as 'biweekly', which strengthens the case for 'fortnightly' when precision matters.
Easily confused with fortnightly
'Biweekly' is ambiguous in English — it can mean either twice a week or every two weeks — whereas 'fortnightly' unambiguously means every two weeks.