What is the term for a symbol wherein a part of a whole represents the whole?

Question

A number of symbols exist wherein a part of some whole is used to represent the whole. For example, the atom is often used to represent science, even though it is only one concept in a very broad field. Somewhat more controversially, in one particularly well-known statue, Robert E. Lee is used to represent the American Antebellum South and Civil War, even though he was only one figure in a very broad landscape.

Is there a term for such a symbol, where a part of some whole is used to represent the whole?

Answer 1

Icon has various senses, one of which is

a person or thing regarded as a representative symbol

[ODO]

The 'part of a whole' aspect is quite common, though looser relationships may also occur.

Answer 2

Synecdoche

a figure of speech by which a part is put for the whole

Answer 3

All the other answers pretty much answer the question, but if you are still in need of another word, you can consider metonymy. A metonym is a figure of speech consisting of the use of the name of one thing for that of another (of which it is associated). It might not necessarily be a subset representing a whole but it's sometimes close enough.

The location of a capital is often used as a metonym for a government or other official institutions. Some examples would The Hague for the International Court of Justice or Wall Street for the entire U.S. financial and corporate banking sector or Hollywood for the entire U.S. film industry or Bollywood for the entire Indian film industry or White House and Capitol Hill for the executive and legislative branches, respectively, of the United States Federal Government.

Synecdoche and metalepsis can be considered as specific types of metonymy.