The story
From 18 being the age of majority in many countries.
Etymology from Wiktionary, CC BY-SA 4.0.
18+
Today it means: Suitable only for adults (e.g. adult content or mature audience content); mature, age of majority. Full definition →
Today it means: Suitable only for adults (e.g. adult content or mature audience content); mature, age of majority. Full definition →
From 18 being the age of majority in many countries.
Etymology from Wiktionary, CC BY-SA 4.0.