Identify a few examples of synecdoche and metonymy as they are used in Act 3, scene 1 of Romeo and Juliet.

Metonymy and synecdoche are two figures of speech which are often confused since they are so similar. In metonymy one replaces the name of a thing with another name with which it is closely associated. One of the most popular examples is, 'The pen is mightier than the sword,' where 'pen' refers to writing and 'sword' refers to war or battle.   

In synecdoche, a part of something is used to represent the whole or vice-versa, where the whole is used to represent a smaller part. An example would be where one refers to a person having nice 'wheels.' This is a common reference to a car as the wheels are part of a vehicle. Alternatively, one can say, 'America' won the World Cup.' The reference is obviously not to the entire population of America, but to a part thereof, i.e. the team that represented the country.

There are a number of examples of both synecdoche and metonymy in this particular scene. At the onset, Benvolio tells Mercutio that 'the day is hot.' What he actually means is that the sun is hot, not the day itself. Since there is an association between the sun and heat, this is metonymy. He also refers to 'the Capulets abroad.' In this instance, he is not referring to the entire Capulet clan but to certain members of the family, such as Tybalt and his friends, being out and about. This is synecdoche since the whole is used to refer to a part.

Benvolio further speaks about the 'mad blood stirring.' This is another example of metonymy because of the assumed association between blood and one's emotions. It is not the blood which becomes volatile, but the individual's emotions which are excited. Even though blood can be seen as part of the whole (synecdoche) the reference is, primarily, to heightened emotions.  

Mercutio refers in his response, to 'the operation of the second cup' suggesting the effect of taking a second cup of alcohol. It is not the cup which affects the individual, but its content. Another example of metonymy. The association between the two is clear. It is not synecdoche since the alcohol does not form part of the cup, it is merely contained therein.

Mercutio later asks, 'what eye but such an eye would spy out such a quarrel?' 'Eye' as it is used here is an obvious reference to a person and is, therefore, synecdoche - using a part to refer to the whole. 

There are quite a few other examples of both metonymy and synecdoche in the rest of the scene. One can look at, for example, the reference to 'fiddlestick' used as metonymy by Mercutio as well as his mention of finding him a 'grave man,' an obvious reference to death, therefore, metonymy. He also pronounces a curse on the Capulets and Montagues by saying, 'A plague on both your houses' (synecdoche).