The meaning of the term "Renaissance man" is basically the same today as when it emerged in Renaissance Italy in the fifteenth century. A term used in Italy was Uomo Universale, meaning Universal Man. The idea is that of a fully-rounded person, someone knowledgeable in many areas, including the sciences, arts, and humanities. Leonardo da Vinci is considered to have been a Renaissance man. In some ways, it is akin to Maslow's concept of self-actualization, the aspiration to be one's own best self, capitalizing on all that one has to offer in a satisfying way. The Renaissance was an emergence from the medieval ages when religion dominated and largely held back development in the sciences and humanities. In the Renaissance, there was a kind of breaking free of the church that allowed for more human-centered intellectual endeavors.
Today, I still hear the term used, but it has become more difficult, I think, to find true Renaissance men or women. Everyone is encouraged to specialize, seldom permitted the luxury to dream and explore, which is necessary to merit the title. I would say that Steven Pinker is a Renaissance man, as he is interested and learned in many areas. When I read his books, I am always amazed at the depth and breadth of his knowledge and understanding. Pinker has deep knowledge about the sciences, humanities, and arts.
As an aside, I think the education system in the United States, in its present state, makes it very difficult to nurture any aspiring Renaissance men or women. Standardized testing, minimizing arts education, and emphasizing job skills do not allow children to inquire, explore, or make connections, all requirements for the development of a Renaissance person.