What does forty mean?
Forty is the cardinal number equal to four tens, following thirty-nine and preceding forty-one. It functions primarily as a noun-numeral in counting and arithmetic, but appears constantly in everyday measurement — forty hours a week, forty miles an hour, page forty — and as a marker of life stages and decades, as in 'she's in her forties'. The word carries rich cultural weight: in biblical tradition, forty signifies a period of trial or completeness, from the forty days of flood to the forty years of wandering in the desert, and idioms such as 'forty winks', meaning a brief nap, keep it current in casual speech. Historically notable phrases like 'forty acres and a mule' anchor it in American history. One practical point: although 'four' contains a 'u', the standard spelling is simply 'forty'; writing 'fourty' is a widespread error. Simple to define yet steeped in tradition, forty is one of English's most culturally loaded numbers.
The cardinal number equal to four tens (40).
"Forty divided by eight is five."
Amounting to forty in number or quantity.
"She collected forty seashells along the shore."
The plural 'forties' refers not to multiple 40s but to the decade of life or a century spanning 40–49 (e.g., 'in his forties', 'the 1940s'). As a pure number, forty does not inflect for plural.
"My father finally learned to swim in his forties."
In the Bible, forty is the classic 'a very long time' number — forty days of rain, forty years in the wilderness — which is why 'forty' still signals an epic ordeal or trial today.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of forty
Forty derives from Old English 'feowertig', formed by combining 'feower' (four) with '-tig', the Germanic suffix for groups of ten that also gave us 'twenty', 'thirty', and 'fifty'. It thus descends from the Proto-Germanic root underlying 'four', whose wider Indo-European cognates include Latin 'quattuor' — the source of 'quarter' and 'quart'. The modern spelling settled without the 'u' of 'four', which is why 'fourty' never became standard.
Related word forms
How forty is actually used
As a numeral, forty is written identically in formal and informal contexts and takes no plural in ordinary counting; however, 'the forties' and 'in her forties' treat it as a plural-like decade label. Note that the common spelling 'fourty' is incorrect — the standard form has no 'u', unlike 'four'. The idiomatic 'forty winks' means a short nap.
Easily confused with forty
Fourteen is the number 14 (four plus ten), while forty is 40 (four times ten); they differ greatly in value despite sharing the element 'four'.