one-fifth
UK[ˌwʌn ˈfɪfθ]US[ˌwʌn ˈfɪfθ]
n
One of five equal parts of something; the fraction equal to 1 divided by 5.
Morpheme Breakdown
one
fifth
one
numeral
fifth
ordinal number
Etymology
The compound "one-fifth" is a transparent and logical construction in English, directly combining the cardinal number "one" with the ordinal number "fifth." The word "one" has a deep lineage tracing back to the Proto-Indo-European root óynos, which carried the fundamental concept of singularity. "Fifth" derives from "five," a numeral whose Proto-Indo-European ancestor, pénkʷe, is remarkably stable across many language families. The suffix "-th," used to form ordinals, is a native English development from Old English '-þa' or '-the'. Therefore, the term's etymology is a straightforward fusion of two ancient numerical concepts, creating a precise term for a fractional quantity, literally meaning "the first of five equal parts."
Analysis
Structure: one (numeral) + fifth (ordinal number)
- one: From Old English 'ān', meaning the cardinal number one. Its ultimate origin is Proto-Indo-European óynos.
- fifth: From Old English 'fīfta', the ordinal form of 'fīf' (five), with the suffix '-th' forming ordinals. 'Fīf' originates from Proto-Germanic fimf, from Proto-Indo-European pénkʷe.
Examples
Approximately one-fifth of the city's population attended the festival.
The recipe calls for one-fifth of a cup of honey.
He pledged to donate one-fifth of his annual income to charity.