I am just curious about why ‘a pretty penny’ in ‘cost someone a pretty penny’. Should I see the ‘penny’ here as just standing for ‘money’? If so, should I suppose that in old days, ‘a penny’ was quite a large amout of money?
Your assumption sounds reasonable to me. According to the Online Etymology Dictionary, the first recorded usage of the phrase ‘a pretty penny’ was in 1768 – and I guess a penny did buy quite a bit more back then. etymonline.com/?term=pretty
I think the word ‘penny’ is simply used in your expression as a sort of representative of money - the technical words for this sort of figure of speech are: metonym or synecdoche where the part represents the whole ie ‘penny’ for ‘money’.
Interestingly the word ‘penny’ crops up in several expressions, two of which suggest the small value of the penny:
if you are going to spend a little money on a venture, you might as well spend a lot more. You’ll find these articles have little value now as they are now two a penny.
A
That is an interesting euphemism, but I’ve only heard it used by Brits. Twenty-five cents seems to be the going price for using a pay toilet in the US nowadays, but twenty-five pennies won’t get you in the door – you generally have to have a quarter.