eighteen
n.n. the number that comes after seventeen and before nineteen. It is the age when people in many countries are legally considered adults.
n. the cardinal number equivalent to the sum of ten and eight. Often used as a noun to refer to a set of this many units or the age of majority.
There are eighteen students in my English class.
You must be eighteen years old to vote in the national election this November.
The historical archive contains eighteen volumes of handwritten letters that document the daily lives of the city's early settlers during the industrial revolution.
From Middle English eightetene, eiȝtene, ehtetene, from Old English eahtatīene, eahtatēne, from Proto-Germanic *ahtōutehun. Cognate with West Frisian achttjin, Dutch achttien, German achtzehn, Danish atten. Equivalent to eight + -teen
Functions as both a determiner before a noun and as a noun in its own right.