noun
18+ only; R-18; adults only
Indicates content or products restricted to those 18 years or older, similar to an age rating. Common in media, games, and online platforms.
このゲームは18禁だから、子どもには買えない。
This game is 18+ only, so I can't buy it for children.
サイトに18禁のマークが表示された。
An 18+ only mark was displayed on the site.
R-18 is the English-derived rating term, while 18禁 is the Japanese abbreviation for '18禁' (18 prohibited). Both mean the same but 18禁 is more colloquial in Japanese.
Abbreviation of 十八 (18) and 禁止 (prohibition), literally '18 prohibited'. A modern coinage for age restriction labeling.