What does fifty mean?
Fifty is the cardinal number equal to five times ten, written as 50 or, in Roman numerals, as L. It serves both as an adjective modifying nouns ('fifty pages') and as a noun in its own right ('a fifty in his hand', 'choose fifty from the list'). Beyond pure counting, fifty carries rich idiomatic weight: to go 'fifty-fifty' is to divide something equally, while 'in his fifties' refers to the decade of life between ages fifty and fifty-nine, and 'the Fifties' evokes the cultural era of the 1950s. The word derives from Old English 'fifting', a combination of 'fif' (five) and the '-tig' suffix denoting groups of ten, linking it etymologically to 'five', 'fifteen', and ultimately the Indo-European root behind Greek 'pente' (as in 'pentagon') and Latin 'quinque' (as in 'quintet'). Familiar, versatile, and numerically central, fifty marks half of a hundred and remains one of the most frequently used round numbers in everyday English.
Being five more than forty; the number 50 used to quantify a noun.
"The marathon route spans fifty kilometres."
Numerals like fifty are typically classified as adjectives when they precede a noun, though many grammars treat them as determiners or quantifiers.
The number 50 itself, or a group/amount of fifty things or people.
"Only fifty of the two hundred applicants were invited to interview."
The decade of a person's life between ages fifty and fifty-nine, or the years 50–59 of a given century (often capitalized for the latter).
"She remained an avid hiker well into her fifties."
'The fifties' (lowercase) usually refers to age, while 'the Fifties' often denotes the 1950s decade in historical contexts.
The plural 'fifties' is used almost exclusively to denote decades of age or of a century; the plural of the plain number is not normally written out in running text.
"Both brothers are in their fifties."
Split something 'fifty-fifty' and you're using an expression that's been dividing things evenly in English since the early 20th century.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fifty
Fifty descends from Old English 'fiftig', formed by combining 'fif' (five) with '-tig', a suffix meaning a group of ten, the same pattern that produced twenty, thirty, and forty. Cognates appear across the Germanic languages, including German 'fünfzig' and Dutch 'vijftig'. More distantly, the 'fiv-' element traces back to the Indo-European root '*penkwe', which also yields Greek 'pente' (as in 'pentagon') and Latin 'quinque' (as in 'quintet').
Related word forms
How fifty is actually used
As a numeral, fifty functions attributively before nouns ('fifty dollars') and can stand alone as a pronoun-like noun ('fifty of them'). The plural noun form is used only in reference to decades of age or of a century ('the fifties', 'the Fifties'), where capitalization distinguishes the historical decade from age. In informal speech, figures like 'fifty-odd' or 'fifty-something' indicate approximate quantities.
Easily confused with fifty
Fifteen is the number 15, while fifty is 50; they differ in stress (FIFteen vs FIFty) and in the '-teen' versus '-ty' ending.