|An 1874 definition of “polymath”, as a "person of vast learning", from Charles Krauth’s A Vocabulary of Philosophical Sciences. (Ѻ)|
The best capture of the embodiment of the label ‘polymath’ might well be the following: 
“Doctor Faust the polymath is — as was Goethe the polymath — a man of "a hundred scholarly disciplines" [and] also a natural scientist.”
This labeling of Johann Goethe, the so-called "prince of the mind", as polymath, who mastered over one-hundred disciplines, is similar to the over-common labeling of Athanasius Kircher (1602-1680), the so-called "master of a 100 arts", as a polymath, the former being a mutually-respecting admirer of the work of later.
Whenever the term "polymath" is used there tends to be an underlying psychology to the method in which authors tend to use, which can be divided into four types. The first, and most common, usage of the term “polymath” is by rote regurgitation, owing to either the fact the person has entered common folklore as an established polymath or by virtue of the fact that the author simply copying or following the lead of a previously read biographical description of a person.
The second occurs where the individual being described has so many diversities of occupations or pastimes that it becomes cumbersome to list them all, whereby recourse to the single term polymath results.
The third, being that the author employing the term polymath, if done so with reserved usage—less than two or three assigned polymaths per book, e.g., history of science type publications—gives heavier weight to its usage.
Fourth, being of the more subtle kind, that in which the individual being discussed may be of the lesser known or unknown genius variety and or whose polymathy tends to unique to a specific field and in which the author employing the term is over-biased or unconsciously slanted in their use of the term. An example of this is American physical economist historian Philip Mirowski who, in his 1989 history of physics used in economic theory book More Heat than Light, uses the term polymath exactly four times, once each in reference to William Whewell (1794-1866) and Benoit Mandelbrot (1924-2010), who each may fall into the polymath category, but then uses the term twice in reference to the lesser known Simon Stevin (1548-1620), whose work seems to be in line with Mirowski’s overall agenda.
|Chapter section on Alexander Humboldt, subtitled "German polymath", by cartographer John Clark, which lends more credence to Humboldt as a true polymath, as compared to passing mentions, made by Clark, of the lesser known cartographers Muhammad al-Idrisi and Shiba Kokan as being polymaths. |
The following is a list of commonly known “polymaths”, each individual referenced with a minimum of at least 2-4 respectable citations (although, to note, some references may tend to be slanted towards a particular bias, in which case a minimum of four or more independent references may be needed), unless, of course, the individual goes without saying as being a polymath.
● List of people who have been called a polymath (Wayback) – Wikipedia.
● List of recognized polymaths (section) – Wikidoc.org.
A well-respected polymath assertion would be someone like George Eliot, with a well-established Cox-Buzan IQ of 175, who comments:
“Goethe was last true polymath to walk the earth.”
The IQ show are known mean meta-analysis ranked intelligence quotients of established geniuses, as listed on the genius IQs page, according to which a mean polymath IQ is discerned (IQpolymath=?). The following (under construction) listing, is ranked in descending order of polymath, generally based on pre-established genius IQ ranking, Cox-Buzan genius [CBG], universal genius [UG] ranking, last universal genius [LUG], two cultures genius [TCG], last person to know everything [LPKE] ranking, greatest physicist ever [GPE], among other similar factors:
Johann Goethe (1749-1832) [LPKE] [LUG] [CBG] [TCG] (IQ=230) The above eight established polymaths, with the shown known or estimated IQs, situate the view that "true" polymaths tend to have an average IQ of 196.
Leonardo da Vinci (1452-1519) [UG] (IQ=205)
Gottfried Leibniz (1646-1716) [LUG] (IQ=200) 
Thomas Young (1773-1829) [LPKE] (IQ=200) 
Erwin Schrodinger (1887-1961) [GPE] (IQ=190) 
Alexander Humboldt (1769-1859) (IQ=185) 
John Mill (1806-1873) (IQ=185) 
Benjamin Franklin (1706-1790) (IQ=175) [CBG] 
Other said-to-be polymaths, per citation shown, without known or estimated IQs, are as follows:
William Whewell (1794-1866) 
Benoit Mandelbrot (1924-2010) 
Simon Stevin (1548-1620) 
Casanova (1725–1798) 
Otto Neurath (1882-1945) 
Muhammad al-Idrisi (1099-1165) 
Shiba Kokan (1747-1818) 
G. Evelyn Hutchinson (1903-1991) 
Carl Djerassi (1923-) 
Jagadish Bose (1858-1937) 
|Left: Austrian physicist Erwin Schrodinger labeled as a polymath—a contender for last universal physicists (similar to Enrico Fermi); renowned for his 1942 lecture What is Life?, which might justify his thrusting into the polymathy category—although, to note, he may not necessarily have been a “polymath” in the true sense or traditional sense of the term, being that it is relatively easy to label him quite aptly as a “physicist” and to most he his known as one of the greatest physicists ever, hence categorization as a polymath is a less common labeling.  Right: Depiction of a polymath, from the 2009 Intelligent Life article “The Last Days of the Polymath”, in which Carl Djerassi (1923-), Casanova (1725–1798), and Thomas Young (1773-1829) are classified as polymaths. |
This group, however, may not rightly fall better into the IQ 170 to 180s, give or take.
The following are noted quotes:
“It isn't often that the human race produces a polymath like von Neumann.”— Howard Rheingold (2000), Tools for Thought 
“If any one person in the previous century personified the word polymath, it was von Neumann.”References— Tom Siegfried (2006), A Beautiful Math: John Nash, Game Theory, and the Modern Quest for a Code of Nature 
1. Mirowski, Philip. (1989). More Heat than Light: Economics as Social Physics, Physics as Nature’s Economics (“polymath”, 4 pgs). Cambridge University Press.
2. Fisch, Menachem and Schaffer, Simon. (1991). Wiliam Whewell: a Composite Portrait (polymath, 4 pgs). Clarendon Press.
3. Glick, Thomas F. (2010). What about Darwin? (pg. 474). JHU Press.
4. Zack, Naomi. (2010). The Handy Philosophy Book (polymath, 2 pgs). Visible Ink Press.
5. McGrew, Timothy, Alspector-Kelly, Marc, and Allhoff, Fritz. (2009). The Philosophy of Science: a Historical Anthology (polymath, 5 pgs). Wiley.
6. Kilmister, C.W. (1989). Schrodinger: Centenary Celebration of a Polymath. Cambridge University Press.
7. Pelikan, Jaroslav J. (1997). Faust the Theologian (pg. 37). Yale University Press.
8. Eliot, George, Maertz, Gregory. (2004). Middlemarch: a Study of Provincial Life (pg. 710). Broadview Press.
9. Clark, John O.E. (2005). 100 Maps: the Science, Art, and Politics of Cartography Throughout History (polymath, 4 pgs; §Von Humboldt: German Polymath, pg. 56-). Sterling Publishing Company.
10. Slack, Nancy G. and Wilson, Edward O. (2011). G. Evelyn Hutchinson and the Invention of Modern Ecology (polymath, 12 pgs). Yale University Press.
11. Carr, Edward. (2009). “The Last Days of the Polymath”, Intelligent Life, Autumn.
12. Rheingold, Howard. (2000). Tools for Thought: the History and Future of Mind-Expanding Technology (pg. 66). MIT Press.
13. Siegfried, Tom. (2006). A Beautiful Math: John Nash, Game Theory, and the Modern Quest for a Code of Nature (pg. 28). National Academies Press.
14. Jones, Barry. (2016). Dictionary of World Biography, Third edition (pg. 100). ANU Press.
● Cumming, Edward. (2009). “Polymaths: 20 Living Examples”, MoreIntelligentLife.com, Autumn.
● Polymath – Wikipedia.