Mature people behave like adults in a way that shows they are well developed emotionally 2. Mature - wordreference english dictionary, questions, discussion and forums. Composed of adults, considered as being less susceptible than minors to explicit sexual content, violence, or obscene language, as of a film or stage performance for mature audiences only. Google allows users to search the web for images, news, products, video, and other content. 2 having or showing the qualities of an adult person a mature outlook.