noun
Used in pricing contexts such as admission fees, transportation fares, and event tickets to indicate the adult rate, as opposed to child (小人・しょうにん) or intermediate (中人・ちゅうにん) categories.
See also: 小人 (しょうにん) · 中人 (ちゅうにん)
映画館の大人料金は1800円です。
The adult ticket price at the movie theater is 1800 yen.
このバスでは、大人は220円、小人は110円です。
On this bus, the fare is 220 yen for adults and 110 yen for children.
The reading だいにん is a Sino-Japanese on'yomi reading of 大人, used specifically in fee-related contexts. The more common reading おとな is a native Japanese word.