scholar (as in person who is very knowledgeable in many areas): polymath
[This word and “philomath” are fairly close synonyms, and in most instances a person who is one will likely be the other as well. The distinction is that a philomath is one who loves the learning process, while a polymath is one who already is knowledgeable in many areas.]
A self-educated polymath endowed with formidable charm and considerable intellect, [Benjamin] Franklin quickly became the leading figure in colonial politics, literature, science, and social reform. (Alan Taylor, “For the Benefit of Mr. Kite,” New Republic, 3/19/2001.)
