eighteenth
UK: ˌeɪˈtiːnθ | US: ˌeɪˈtiːnθ
adj. constituting number eighteen in a sequence; 18th
n. the position or item corresponding to number eighteen
The word "eighteenth" combines "eighteen," derived from Old English "eahtatēne" (eahta<eight> + tēne<ten>), with the ordinal suffix "-th," which marks position in a sequence. This suffix traces back to Proto-Germanic *-dô and is used to form ordinal numbers (e.g., fourth, fifth). The logical progression from cardinal ("eighteen") to ordinal ("eighteenth") reflects a consistent pattern in English numbering.
Her birthday falls on the eighteenth of March.
The eighteenth century was marked by significant industrial advancements.
He finished in eighteenth place in the race.
The amendment was ratified on the eighteenth day of the convention.
Chapter eighteen concludes the novel’s central conflict.