If I am writing a poem, I might use the word peaches to symbolize all fruit. Is there a specific word for this type of symbolism?
It's called metonymy. For example, sword for "war" or Washington for "the US Government".
Thurber has a lovely hymn to metonymy, “Here Lies Miss Groby”, in particular to the Container for the Thing Contained…– PLLDec 24, 2010 at 2:55
1So is synecdoche a kind of metonymy?– GEdgarFeb 18, 2012 at 13:51
From Michael Quinion at World Wide Words: worldwidewords.org/qa/qa-syn1.htm <<Both are figures of speech used in rhetoric. They’re not the same thing, though metonymy is often interpreted so widely that synecdoche can be regarded as a special case of it.>> There is a convention to choose the tighter of two hypernymic-hyponymic terms (an application of the 'principle of specificity'), so I'd go with synecdoche here - using the whole to reference the part (England win 2 - 0) or the part to reference the whole (Napoleon had 200 000 foot). Boil a kettle is obviously metonymy but not synecdoche. Jan 11, 2013 at 14:45
If you're interested in a suitable word outside the realm of literary criticism, you might consider exemplar especially if you're looking for the connotation of the single best representation of the many.
Wiktionary gives the definition of:
Something typical or representative of a class
Something fit to be imitated
I'd use "syndedoche" in the sense of the original question- use of a subset of something to represent the whole, e.g. "The colonel commanded two hundred horse", or "Fifty head of cattle"
As I understand it, metonymy is the use of something associated with the described object as a representation of it; "Hollywood" for the film industry, or "Wall Street" for the financial market.
I'd query 'horse' as a subset of 'horseman/horsemen' - this is surely metonymy and not synecdoche. Horse represents horseman, not (horse + horseman). Compare Jesse James and his five guns held up the stagecoach. The head is a part of the neat; the horse is not a part of the horseman. Jan 11, 2013 at 8:59