equivalent to the product of two and nine; one more than seventeen, or eight more than ten; 18:she wrote eighteen novelsout of sixty batches checked, eighteen were incorrecteighteen of the guests were gathered (Roman numeral: xviii or XVIII)
a set or team of eighteen individuals.
eighteen years old:he was barely eighteen
a size of garment or other merchandise denoted by eighteen.
(18)British (of a film) classified as suitable for people of 18 years and over.